fix(espaciados): complete the spacing review across every screen

Finishes the review the user asked for after on-device testing; Buscar
was fixed earlier in fdb7eb1.

- Favoritos' header sat 36px from the edge instead of 20 -- the list's
  own padding stacked on top of PluriRootHeader's inset, and it was the
  one root that did not match Alarmas and Ajustes
- Rows were card-tier (16) where the prototype uses row-tier (12)
- Settings group-to-group gap 12 -> 16; Grabaciones storage card -> rows
  12 -> 16; Paises language -> country list 16 -> 14
- Alarma sonando's snooze block had a non-uniform 10/14 gap pair
- The date line moved below the hero time, where the prototype puts it

Escuchar, Alarmas, Vacaciones, the 12 settings detail screens,
Reproductor and Bienvenida were checked and were already correct.

Tests: 926 -> 933.

lib/pantallas/pantalla_ajustes.dart

@@ -147,7 +147,9 @@ class _AjustesContent extends StatelessWidget {
             ),
           ],
         ),
-        const SizedBox(height: 12),
+        // Issue 3 (feedback-pruebas): t4:523/534/541 all draw a 16px gap
+        // between these opaque, stacked settings groups -- not 12.
+        const SizedBox(height: 16, key: ValueKey('ajustes-group-gap-1')),
         GrupoAjustes(
           titulo: l10n.settingsGroupStationsTitle,
           filas: [
@@ -202,7 +204,7 @@ class _AjustesContent extends StatelessWidget {
             ),
           ],
         ),
-        const SizedBox(height: 12),
+        const SizedBox(height: 16, key: ValueKey('ajustes-group-gap-2')),
         GrupoAjustes(
           titulo: l10n.settingsGroupRecordingsTitle,
           filas: [
@@ -250,7 +252,7 @@ class _AjustesContent extends StatelessWidget {
             ),
           ],
         ),
-        const SizedBox(height: 12),
+        const SizedBox(height: 16, key: ValueKey('ajustes-group-gap-3')),
         GrupoAjustes(
           titulo: l10n.settingsGroupApplicationTitle,
           filas: [

lib/pantallas/pantalla_alarma_sonando.dart

@@ -225,25 +225,6 @@ class _PantallaAlarmaSonandoState extends State<PantallaAlarmaSonando> {
                     tokens: tokens,
                   ),
                   const SizedBox(height: 22),
-                  // Audit 9.4 (t4 line 419): "Lunes, 3 de agosto" between
-                  // the pill and the hero time -- never rendered before.
-                  // Purely additive: a new sibling Text, touching neither
-                  // the pill above nor the hero time below.
-                  Text(
-                    fechaLargaConDiaSemana(
-                      Localizations.localeOf(context).toString(),
-                      DateTime.now(),
-                    ),
-                    textAlign: TextAlign.center,
-                    style: TextStyle(
-                      fontSize: 14,
-                      fontWeight: FontWeight.w600,
-                      color: Theme.of(
-                        context,
-                      ).colorScheme.onSurface.withValues(alpha: 0.6),
-                    ),
-                  ),
-                  const SizedBox(height: 6),
                   FittedBox(
                     fit: BoxFit.scaleDown,
                     child: Text(
@@ -261,6 +242,28 @@ class _PantallaAlarmaSonandoState extends State<PantallaAlarmaSonando> {
                     ),
                   ),
                   const SizedBox(height: 6),
+                  // Audit 9.4: the date line goes BELOW the hero time. The
+                  // prototype's order is pill (t4:415-416) -> 7:30 at 88px
+                  // (t4:417) -> "Lunes, 3 de agosto" at 14px (t4:419). An
+                  // earlier pass placed it between the pill and the time
+                  // and cited "t4 line 419" for it — that line number is
+                  // where the date SITS in the source, which is precisely
+                  // why it comes last, not first.
+                  Text(
+                    fechaLargaConDiaSemana(
+                      Localizations.localeOf(context).toString(),
+                      DateTime.now(),
+                    ),
+                    textAlign: TextAlign.center,
+                    style: TextStyle(
+                      fontSize: 14,
+                      fontWeight: FontWeight.w600,
+                      color: Theme.of(
+                        context,
+                      ).colorScheme.onSurface.withValues(alpha: 0.6),
+                    ),
+                  ),
+                  const SizedBox(height: 6),
                   Text(
                     localizedAlarmName(l10n, alarma.nombre),
                     textAlign: TextAlign.center,
@@ -339,14 +342,18 @@ class _PantallaAlarmaSonandoState extends State<PantallaAlarmaSonando> {
                       ],
                     ),
                   ),
-                  const SizedBox(height: 10),
+                  // Issue 3 (feedback-pruebas): t4:427 wraps POSPONER's
+                  // eyebrow, the snooze tiles and Stop in a `gap:12` flex
+                  // column -- the same 12 on both sides, not the 10/14 pair
+                  // this used to carry.
+                  const SizedBox(height: 12),
                   _FilaSnoozeFija(
                     alarma: alarma,
                     l10n: l10n,
                     tokens: tokens,
                     onPosponer: _posponer,
                   ),
-                  const SizedBox(height: 14),
+                  const SizedBox(height: 12),
                   SizedBox(
                     width: double.infinity,
                     child: FilledButton.icon(

lib/pantallas/pantalla_favoritos.dart

@@ -174,12 +174,18 @@ class _PantallaFavoritosState extends State<PantallaFavoritos> {
 
     return ReorderableListView(
       buildDefaultDragHandles: false,
-      padding: const EdgeInsets.fromLTRB(
-        PluriLayout.horizontal,
-        4,
-        PluriLayout.horizontal,
-        PluriLayout.bottomChromeInset,
-      ),
+      // Issue 3 (feedback-pruebas): zero horizontal here, matching every
+      // other root's PluriLayout.pageListPadding convention (Alarmas,
+      // Ajustes, and this screen's OWN empty-state branch above).
+      // ReorderableListView.padding wraps header/children/footer UNIFORMLY,
+      // so a single horizontal value here can never be simultaneously right
+      // for PluriRootHeader (self-padded, wants none), the reorderable rows
+      // (want row tier, applied per item below) and the footer CTA (wants
+      // card tier, applied on the footer's own Padding below). The previous
+      // `PluriLayout.horizontal` doubled up on top of PluriRootHeader's own
+      // internal inset, pushing "Favorites" in by 36px instead of the 20px
+      // every other root uses for its title.
+      padding: const EdgeInsets.only(bottom: PluriLayout.bottomChromeInset),
       header: Padding(
         padding: const EdgeInsets.only(bottom: 12),
         child: Column(
@@ -224,17 +230,39 @@ class _PantallaFavoritosState extends State<PantallaFavoritos> {
               ],
             ),
             const SizedBox(height: 12),
-            _FilaChipsGrupos(
-              grupos: gruposVisibles,
-              favoritos: favoritos,
-              seleccionado: seleccionEfectiva,
-              onSeleccionar: (id) => setState(() => _grupoSeleccionadoId = id),
+            // Issue 3 (feedback-pruebas): t4:218 draws this chip strip at
+            // title-tier (20px) horizontal inset, directly on the page
+            // background -- it now needs its OWN inset since the list's
+            // padding no longer supplies one.
+            Padding(
+              padding: const EdgeInsets.symmetric(
+                horizontal: PluriLayout.titleHorizontal,
+              ),
+              child: _FilaChipsGrupos(
+                grupos: gruposVisibles,
+                favoritos: favoritos,
+                seleccionado: seleccionEfectiva,
+                onSeleccionar:
+                    (id) => setState(() => _grupoSeleccionadoId = id),
+              ),
             ),
           ],
         ),
       ),
       footer: Padding(
-        padding: const EdgeInsets.only(top: 4),
+        // Issue 3 (feedback-pruebas): card tier (16, matching every other
+        // screen's dashed CTA) now that the list's own padding no longer
+        // supplies it, plus t4:234's 8px gap above the CTA
+        // (PluriLayout.compactGap) instead of the previous unwired literal
+        // 4 -- the ONLY state of this screen with a nonzero top gap before
+        // its own content used a value that matched neither this screen's
+        // own empty-state branch nor the prototype.
+        padding: const EdgeInsets.fromLTRB(
+          PluriLayout.horizontal,
+          PluriLayout.compactGap,
+          PluriLayout.horizontal,
+          0,
+        ),
         child: _CtaEmisoraPersonalizada(
           onTap: _abrirFormularioEmisoraPersonalizada,
         ),
@@ -244,14 +272,24 @@ class _PantallaFavoritosState extends State<PantallaFavoritos> {
               _onReorder(filtrados, favoritos, oldIndex, newIndex),
       children: [
         for (var i = 0; i < filtrados.length; i++)
-          _FilaFavorito(
+          // Issue 3 (feedback-pruebas): row tier (12), not card tier -- the
+          // key moves to this wrapper (ReorderableListView identifies each
+          // child by its own top-level key) since FilaEmisoraPlana rows are
+          // documented (audit 4.3) as flat, background-less rows, the same
+          // tier Buscar's results list already uses for the same widget.
+          Padding(
             key: ValueKey(filtrados[i].uuid),
-            index: i,
-            emisora: filtrados[i],
-            grupos: gruposVisibles,
-            grupoActual: gruposVisibles.firstWhere(
-              (g) => g.id == filtrados[i].grupoFavoritosId,
-              orElse: () => gruposVisibles.first,
+            padding: const EdgeInsets.symmetric(
+              horizontal: PluriLayout.rowHorizontal,
+            ),
+            child: _FilaFavorito(
+              index: i,
+              emisora: filtrados[i],
+              grupos: gruposVisibles,
+              grupoActual: gruposVisibles.firstWhere(
+                (g) => g.id == filtrados[i].grupoFavoritosId,
+                orElse: () => gruposVisibles.first,
+              ),
             ),
           ),
       ],
@@ -343,7 +381,6 @@ class _FilaChipsGrupos extends StatelessWidget {
 
 class _FilaFavorito extends StatelessWidget {
   const _FilaFavorito({
-    super.key,
     required this.index,
     required this.emisora,
     required this.grupos,

lib/pantallas/pantalla_grabaciones.dart

@@ -251,7 +251,12 @@ class _PantallaGrabacionesState extends State<PantallaGrabaciones> {
             padding: PluriLayout.pageContentPadding,
             children: [
               _BarraDeAlmacenamiento(archivos: archivos),
-              const SizedBox(height: 12),
+              // Issue 3 (feedback-pruebas): t4:617 draws a 16px gap between
+              // the storage card and the rows below it, not 12.
+              const SizedBox(
+                height: 16,
+                key: ValueKey('grabaciones-storage-gap'),
+              ),
               if (snap.connectionState == ConnectionState.done &&
                   archivos.isEmpty)
                 PluriEmptyState(

lib/pantallas/pantalla_paises.dart

@@ -134,7 +134,12 @@ class _PantallaPaisesState extends State<PantallaPaises> {
                     ),
                   if (query.isEmpty) ...[
                     _seccionTusIdiomas(context, estado.paises, l10n),
-                    const SizedBox(height: 16),
+                    // Issue 3 (feedback-pruebas): t4:260 draws a 14px gap
+                    // between "Tus idiomas" and "Todos", not 16.
+                    const SizedBox(
+                      height: 14,
+                      key: ValueKey('paises-seccion-gap'),
+                    ),
                     _seccionTodos(context, estado.paises, l10n),
                   ] else
                     _seccionTodos(context, paisesFiltrados, l10n),

test/pantallas/pantalla_ajustes_test.dart

@@ -306,6 +306,32 @@ void main() {
       expect(find.text('RECORDINGS & MUSIC'), findsOneWidget);
       expect(find.text('APPLICATION'), findsOneWidget);
     });
+
+    testWidgets(
+      'Issue 3 (feedback-pruebas): the gap between stacked settings groups '
+      'is 16, matching t4:523/534/541 -- not 12',
+      (tester) async {
+        setLargeSurface(tester);
+        _suppressListTileInkAssertion();
+        final estado = await crearEstado();
+        addTearDown(estado.dispose);
+
+        await tester.pumpWidget(buildAjustes(estado));
+        await pumpStable(tester);
+
+        for (final key in [
+          'ajustes-group-gap-1',
+          'ajustes-group-gap-2',
+          'ajustes-group-gap-3',
+        ]) {
+          expect(
+            tester.getSize(find.byKey(ValueKey(key))).height,
+            16,
+            reason: 't4:523/534/541 all draw a 16px gap between stacked groups',
+          );
+        }
+      },
+    );
   });
 }
 

test/pantallas/pantalla_alarma_sonando_tier5_test.dart

@@ -99,8 +99,8 @@ void main() {
     SharedPreferences.setMockInitialValues({});
   });
 
-  testWidgets('visual fidelity (audit 9.4): the date line renders between the '
-      'schedule pill and the hero time (t4:419)', (tester) async {
+  testWidgets('visual fidelity (audit 9.4): the date line renders BELOW the '
+      'hero time (t4:415-419: pill, then 7:30, then the date)', (tester) async {
     await _montarPantalla(tester);
 
     final localeTag =
@@ -111,16 +111,22 @@ void main() {
 
     expect(find.text(esperado), findsOneWidget);
 
-    // Order: pill above the date line, date line above the hero time.
+    // Order: pill, then the hero time, then the date line. This test used
+    // to assert date-before-time and cited "t4:419" for it — but 419 is
+    // simply the source line the date occupies, and in the prototype it
+    // comes AFTER the 88px time on line 417. The citation refuted the
+    // assertion it was supporting.
     final pillY =
         tester
             .getBottomLeft(find.byKey(const ValueKey('ringing-schedule-pill')))
             .dy;
-    final dateY = tester.getTopLeft(find.text(esperado)).dy;
     final timeY =
-        tester.getTopLeft(find.byKey(const ValueKey('ringing-hero-time'))).dy;
-    expect(pillY <= dateY, isTrue);
-    expect(dateY <= timeY, isTrue);
+        tester
+            .getBottomLeft(find.byKey(const ValueKey('ringing-hero-time')))
+            .dy;
+    final dateY = tester.getTopLeft(find.text(esperado)).dy;
+    expect(pillY <= timeY, isTrue, reason: 'pill sits above the time');
+    expect(timeY <= dateY, isTrue, reason: 'the date sits below the time');
 
     // Regression guard: pumpAndSettle must still complete (purely
     // additive static text, no new animation).
@@ -159,4 +165,49 @@ void main() {
       await tester.pumpAndSettle();
     },
   );
+
+  testWidgets(
+    'Issue 3 (feedback-pruebas): the gap above the snooze tiles matches the '
+    'gap below them (t4:427 draws a uniform gap:12 flex column) -- the '
+    'previous 10/14 pair matched neither the prototype nor each other',
+    (tester) async {
+      await _montarPantalla(tester);
+      final l10n = AppLocalizations.of(
+        tester.element(find.byType(PantallaAlarmaSonando)),
+      );
+
+      final eyebrowBottom =
+          tester
+              .getBottomLeft(
+                find
+                    .ancestor(
+                      of: find.byIcon(Icons.snooze_rounded),
+                      matching: find.byType(Row),
+                    )
+                    .first,
+              )
+              .dy;
+      final tileDestacado = find.ancestor(
+        of: find.text(l10n.alarmSnoozeOptionLabel(10)),
+        matching: find.byType(FilledButton),
+      );
+      final tilesTop = tester.getTopLeft(tileDestacado).dy;
+      final tilesBottom = tester.getBottomLeft(tileDestacado).dy;
+      final stopButtonTop =
+          tester
+              .getTopLeft(find.byKey(const ValueKey('ringing-stop-button')))
+              .dy;
+
+      expect(
+        tilesTop - eyebrowBottom,
+        12,
+        reason: 't4:427: gap:12 above the snooze tiles',
+      );
+      expect(
+        stopButtonTop - tilesBottom,
+        12,
+        reason: 't4:427: gap:12 below the snooze tiles, same as above',
+      );
+    },
+  );
 }

test/pantallas/pantalla_favoritos_test.dart

@@ -7,7 +7,9 @@ import 'package:pluriwave/l10n/gen/app_localizations.dart';
 import 'package:pluriwave/pantallas/ajustes/pantalla_ajustes_grupos_favoritos.dart';
 import 'package:pluriwave/pantallas/pantalla_favoritos.dart';
 import 'package:pluriwave/widgets/fila_emisora_plana.dart';
+import 'package:pluriwave/widgets/pluri_layout.dart';
 import 'package:pluriwave/widgets/pluri_push_scaffold.dart';
+import 'package:pluriwave/widgets/pluri_root_header.dart';
 import 'package:pluriwave/widgets/tarjeta_emisora.dart';
 import 'package:provider/provider.dart';
 import 'package:shared_preferences/shared_preferences.dart';
@@ -546,6 +548,106 @@ void main() {
       expect(inactivo.backgroundColor, const Color(0xFF102532));
     });
   });
+
+  group('Issue 3 (feedback-pruebas): spacing tiers', () {
+    testWidgets('the header title sits at title-tier inset (20px) -- '
+        'ReorderableListView.padding used to double up on top of '
+        "PluriRootHeader's own internal inset", (tester) async {
+      setLargeSurface(tester);
+      _suppressListTileInkAssertion();
+      final estado = await crearEstadoConFavoritos();
+      addTearDown(estado.dispose);
+      final l10n = lookupAppLocalizations(const Locale('en'));
+
+      await tester.pumpWidget(buildScreen(estado));
+      await pumpStable(tester);
+
+      final titulo = find.descendant(
+        of: find.byType(PluriRootHeader),
+        matching: find.text(l10n.favoritesTitle),
+      );
+      expect(
+        tester.getTopLeft(titulo).dx,
+        PluriLayout.titleHorizontal,
+        reason:
+            'PluriRootHeader already supplies its own 20px inset; the '
+            'previous ReorderableListView.padding of 16 doubled up on top '
+            'of it, landing the title at 36px instead of 20px -- the ONE '
+            "root screen whose header didn't match Alarmas/Ajustes",
+      );
+    });
+
+    testWidgets(
+      'the header sits at the SAME horizontal position whether the list is '
+      'empty or populated -- two mutually-exclusive states of the same '
+      'header must not read differently',
+      (tester) async {
+        setLargeSurface(tester);
+        final l10n = lookupAppLocalizations(const Locale('en'));
+
+        final vacio = await crearEstadoVacio();
+        addTearDown(vacio.dispose);
+        await tester.pumpWidget(buildScreen(vacio));
+        await pumpStable(tester);
+        final dxVacio =
+            tester
+                .getTopLeft(
+                  find.descendant(
+                    of: find.byType(PluriRootHeader),
+                    matching: find.text(l10n.favoritesTitle),
+                  ),
+                )
+                .dx;
+
+        _suppressListTileInkAssertion();
+        final conFavoritos = await crearEstadoConFavoritos();
+        addTearDown(conFavoritos.dispose);
+        await tester.pumpWidget(buildScreen(conFavoritos));
+        await pumpStable(tester);
+        final dxConFavoritos =
+            tester
+                .getTopLeft(
+                  find.descendant(
+                    of: find.byType(PluriRootHeader),
+                    matching: find.text(l10n.favoritesTitle),
+                  ),
+                )
+                .dx;
+
+        expect(
+          dxConFavoritos,
+          dxVacio,
+          reason:
+              'the empty and populated branches of this screen must render '
+              'the SAME header inset -- they previously did not (0 vs 16 '
+              'extra px of list-level padding)',
+        );
+      },
+    );
+
+    testWidgets(
+      'each favourite row uses row-tier horizontal inset (12), not the '
+      'card-tier constant a background-less row was never meant to carry',
+      (tester) async {
+        setLargeSurface(tester);
+        _suppressListTileInkAssertion();
+        final estado = await crearEstadoConFavoritos();
+        addTearDown(estado.dispose);
+
+        await tester.pumpWidget(buildScreen(estado));
+        await pumpStable(tester);
+
+        expect(
+          tester.getTopLeft(find.byType(FilaEmisoraPlana).first).dx,
+          PluriLayout.rowHorizontal,
+          reason:
+              'audit 4.3: background-less rows are row tier (12), matching '
+              'the same widget already fixed on Buscar -- not card tier '
+              '(16)',
+        );
+      },
+    );
+  });
 }
 
 void setLargeSurface(WidgetTester tester) {

test/pantallas/pantalla_grabaciones_test.dart

@@ -216,6 +216,35 @@ void main() {
     },
   );
 
+  testWidgets(
+    'Issue 3 (feedback-pruebas): the gap between the storage card and the '
+    'rows below is 16, matching t4:617 -- not 12',
+    (tester) async {
+      final estado = EstadoGrabacion(
+        servicio: _FakeServicioGrabacionConArchivos([
+          fijaA,
+        ], maxBytesFijo: 200 * 1024 * 1024),
+      );
+      addTearDown(estado.dispose);
+
+      await tester.pumpWidget(
+        buildScreen(
+          estado: estado,
+          reproductor: _ReproductorGrabacionesFake(const {}),
+        ),
+      );
+      await pumpStable(tester);
+
+      expect(
+        tester
+            .getSize(find.byKey(const ValueKey('grabaciones-storage-gap')))
+            .height,
+        16,
+        reason: 't4:617 draws a 16px gap here',
+      );
+    },
+  );
+
   testWidgets('15.2-A: 3 recording fixtures render as 3 rows', (tester) async {
     final estado = EstadoGrabacion(
       servicio: _FakeServicioGrabacionConArchivos([

test/pantallas/pantalla_paises_test.dart

@@ -262,6 +262,27 @@ void main() {
 
       expect(find.byIcon(Icons.search_rounded), findsOneWidget);
     });
+
+    testWidgets('Issue 3 (feedback-pruebas): the gap between "Tus idiomas" and '
+        '"Todos" is 14, matching t4:260 -- not 16', (tester) async {
+      final estado = EstadoBusqueda(
+        radio: FakeServicioRadio(
+          paises: const [
+            PaisRadio(nombre: 'Spain', codigoIso: 'ES', numeroEmisoras: 482),
+          ],
+        ),
+      );
+      addTearDown(estado.dispose);
+
+      await tester.pumpWidget(buildScreen(estado));
+      await pumpEstable(tester);
+
+      expect(
+        tester.getSize(find.byKey(const ValueKey('paises-seccion-gap'))).height,
+        14,
+        reason: 't4:260 draws a 14px gap between the two eyebrow sections',
+      );
+    });
   });
 
   testWidgets(