fix(chrome): rebuild MiniReproductor as a full-bleed opaque bar with art

Item 22 / audit 3.6 (t4:184-188): the mini player was a floating
999-radius glass pill with no artwork. Replace it with a 60px opaque
bar (listSurface at .97 alpha), full-bleed edge to edge, showing the
station's square 42x42 artwork instead of the abstract playing-bars
indicator. app.dart no longer wraps the bar in the balloon nav's own
8px side margin, so it now spans the full width.

MiniReproductor.altura is re-measured (72 -> 60) now that the bar's
content height is fixed by construction; PluriLayout.bottomChromeInset
derives from it as before. Both the S3-R3 configurarLocalizaciones
guard and the altura measurement test still pass unmodified.

test/widgets/mini_reproductor_barra_test.dart

@@ -0,0 +1,141 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pluriwave/estado/estado_radio.dart';
+import 'package:pluriwave/l10n/gen/app_localizations.dart';
+import 'package:pluriwave/tema/pluriwave_theme.dart';
+import 'package:pluriwave/tema/pluriwave_tokens.dart';
+import 'package:pluriwave/widgets/mini_reproductor.dart';
+import 'package:pluriwave/widgets/visualizador_audio.dart';
+import 'package:provider/provider.dart';
+
+import '../helpers/fakes.dart';
+import '../helpers/fakes_alarmas.dart';
+
+EstadoRadio _estadoConEmisora() {
+  return EstadoRadio(
+    audio: FakeServicioAudio(),
+    favoritos: FakeServicioFavoritos(),
+    radio: FakeServicioRadio(),
+    servicioEcualizador: FakeServicioEcualizador(),
+    servicioGrabacion: FakeServicioGrabacionRadioInactiva(),
+    iniciarAutomaticamente: false,
+  );
+}
+
+Widget _hostFor(EstadoRadio estado, {double width = 390}) {
+  return ChangeNotifierProvider<EstadoRadio>.value(
+    value: estado,
+    child: MaterialApp(
+      theme: PluriWaveTheme.dark(),
+      locale: const Locale('es'),
+      localizationsDelegates: AppLocalizations.localizationsDelegates,
+      supportedLocales: AppLocalizations.supportedLocales,
+      home: Scaffold(
+        body: SizedBox(width: width, child: const MiniReproductor()),
+      ),
+    ),
+  );
+}
+
+/// Item 22 / audit 3.6 (t4:184-188): the mini player becomes a 60px
+/// full-bleed opaque bar with station artwork, replacing the floating
+/// 999-radius glass pill with no artwork.
+void main() {
+  testWidgets(
+    'shows the station artwork (42x42, radius 11) instead of the playing-'
+    'bars indicator',
+    (tester) async {
+      final estado = _estadoConEmisora();
+      addTearDown(estado.dispose);
+      await estado.reproducir(emisoraDemo(uuid: 'a', nombre: 'Station A'));
+
+      await tester.pumpWidget(_hostFor(estado));
+      await tester.pump();
+
+      expect(
+        find.byType(IndicadorReproduccion),
+        findsNothing,
+        reason: 't4:186 replaces the playing-bars indicator with artwork',
+      );
+
+      final arte = find.byKey(const ValueKey('mini-reproductor-arte'));
+      expect(arte, findsOneWidget);
+      expect(
+        tester.getSize(arte),
+        const Size(42, 42),
+        reason: 't4:186 art is 42x42',
+      );
+
+      final clip = tester.widget<ClipRRect>(arte);
+      expect(
+        (clip.borderRadius as BorderRadius).topLeft,
+        const Radius.circular(11),
+        reason: 't4:186 art corner radius is 11',
+      );
+    },
+  );
+
+  testWidgets(
+    'is opaque -- no BackdropFilter -- unlike the former glass pill',
+    (tester) async {
+      final estado = _estadoConEmisora();
+      addTearDown(estado.dispose);
+      await estado.reproducir(emisoraDemo(uuid: 'a', nombre: 'Station A'));
+
+      await tester.pumpWidget(_hostFor(estado));
+      await tester.pump();
+
+      expect(
+        find.descendant(
+          of: find.byType(MiniReproductor),
+          matching: find.byType(BackdropFilter),
+        ),
+        findsNothing,
+        reason:
+            't4:185 the bar is opaque rgba(16,37,50,.97), not blurred glass',
+      );
+    },
+  );
+
+  testWidgets(
+    'fill colour is listSurface at .97 alpha (t4:185 rgba(16,37,50,.97))',
+    (tester) async {
+      final estado = _estadoConEmisora();
+      addTearDown(estado.dispose);
+      await estado.reproducir(emisoraDemo(uuid: 'a', nombre: 'Station A'));
+
+      await tester.pumpWidget(_hostFor(estado));
+      await tester.pump();
+
+      final decorado = tester.widget<DecoratedBox>(
+        find.byKey(const ValueKey('mini-reproductor-superficie')),
+      );
+      final decoration = decorado.decoration as BoxDecoration;
+      expect(
+        decoration.color,
+        PluriWaveTokens.dark.listSurface.withValues(alpha: 0.97),
+      );
+    },
+  );
+
+  testWidgets('the opaque surface spans the full given width -- no internal '
+      'horizontal margin (t4:185 left:0;right:0)', (tester) async {
+    final estado = _estadoConEmisora();
+    addTearDown(estado.dispose);
+    await estado.reproducir(emisoraDemo(uuid: 'a', nombre: 'Station A'));
+
+    await tester.pumpWidget(_hostFor(estado, width: 390));
+    await tester.pump();
+
+    expect(
+      tester
+          .getSize(find.byKey(const ValueKey('mini-reproductor-superficie')))
+          .width,
+      390,
+      reason:
+          't4:185 the bar is full-bleed, not a margined floating pill -- '
+          'the OLD implementation wrapped this in 24px of horizontal '
+          'padding per side (8 from app.dart + 16 internal)',
+    );
+  });
+}

test/widgets/pluri_bottom_navigation_test.dart

@@ -194,16 +194,12 @@ void main() {
     semantics.dispose();
   });
 
-  testWidgets('every tab meets the 48x48dp minimum tap target', (
-    tester,
-  ) async {
+  testWidgets('every tab meets the 48x48dp minimum tap target', (tester) async {
     await tester.pumpWidget(hostFor(0));
     await tester.pump();
 
     for (var i = 0; i < items.length; i++) {
-      final size = tester.getSize(
-        find.byKey(PluriBottomNavigation.itemKey(i)),
-      );
+      final size = tester.getSize(find.byKey(PluriBottomNavigation.itemKey(i)));
       expect(size.width, greaterThanOrEqualTo(48));
       expect(size.height, greaterThanOrEqualTo(48));
     }
@@ -248,22 +244,23 @@ void main() {
               bottomNavigationBar: SafeArea(
                 key: chromeKey,
                 top: false,
-                minimum: const EdgeInsets.only(
-                  bottom: PluriLayout.compactGap,
-                ),
-                child: Padding(
-                  padding: const EdgeInsets.fromLTRB(8, 0, 8, 0),
-                  child: Column(
-                    mainAxisSize: MainAxisSize.min,
-                    children: [
-                      const MiniReproductor(),
-                      PluriBottomNavigation(
+                minimum: const EdgeInsets.only(bottom: PluriLayout.compactGap),
+                child: Column(
+                  mainAxisSize: MainAxisSize.min,
+                  children: [
+                    // Mirrors app.dart's real composition: item 22 / audit
+                    // 3.6 made MiniReproductor full-bleed, so only
+                    // PluriBottomNavigation keeps the 8px side margin.
+                    const MiniReproductor(),
+                    Padding(
+                      padding: const EdgeInsets.fromLTRB(8, 0, 8, 0),
+                      child: PluriBottomNavigation(
                         items: items,
                         selectedIndex: 0,
                         onSelected: (_) {},
                       ),
-                    ],
-                  ),
+                    ),
+                  ],
                 ),
               ),
             ),