feat(ui): design token discipline, accessibility and i18n pass

- Replace all hardcoded Color literals outside lib/tema with theme tokens (new static brand palette in PluriWaveTokens); media notification uses the brand color instead of the Material default purple
- Favorite button on station cards grows to a 48dp target and becomes an independent semantics node for screen readers (Semantics container fix)
- All flutter_animate call sites route through the PluriAnimate reduced-motion gate (zero direct .animate() left)
- Locale-aware short dates via intl DateFormat (new lib/l10n/formato_fechas.dart) replacing the hardcoded DD/MM/YYYY; proper plural messages for the favorites counter; example stream URL as a localized key - all 13 locales
- Rounded shimmer placeholders matching card radii; shimmer loading state in search instead of a bare spinner; rounded icon variants unified in settings; bottom-sheet conventions on the custom station form
- Fix latent debug crash: vacation editor read AppLocalizations in initState
- 11 new tests (121 total green), flutter analyze clean

test/pantallas/pantalla_alarmas_fecha_test.dart

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+import 'package:flutter_test/flutter_test.dart';
+import 'package:intl/date_symbol_data_local.dart';
+import 'package:intl/intl.dart';
+import 'package:pluriwave/l10n/formato_fechas.dart';
+
+/// S5-R4: short dates must follow the active locale, not a hardcoded
+/// DD/MM/YYYY pattern.
+void main() {
+  test('en-US usa el orden mes/día, no el formato fijo DD/MM/YYYY', () {
+    final fecha = DateTime(2026, 6, 11);
+    final resultado = fechaCortaLocalizada('en-US', fecha);
+
+    expect(resultado, DateFormat.yMd('en-US').format(fecha));
+    expect(resultado, isNot('11/06/2026'));
+    expect(resultado, '6/11/2026');
+  });
+
+  test('es usa el orden día/mes', () async {
+    await initializeDateFormatting('es');
+    final fecha = DateTime(2026, 6, 11);
+
+    expect(
+      fechaCortaLocalizada('es', fecha),
+      DateFormat.yMd('es').format(fecha),
+    );
+  });
+}

test/pantallas/pantalla_buscar_shimmer_test.dart

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+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pluriwave/estado/estado_busqueda.dart';
+import 'package:pluriwave/l10n/gen/app_localizations.dart';
+import 'package:pluriwave/pantallas/pantalla_buscar.dart';
+import 'package:pluriwave/widgets/tarjeta_emisora.dart';
+import 'package:provider/provider.dart';
+
+import '../helpers/fakes.dart';
+
+/// S5-R6: the search loading state uses shimmer placeholders, not a bare
+/// spinner, to stay consistent with the rest of the app.
+class _BusquedaCargando extends EstadoBusqueda {
+  _BusquedaCargando() : super(radio: FakeServicioRadio());
+
+  @override
+  bool get cargando => true;
+}
+
+void main() {
+  testWidgets('PantallaBuscar muestra shimmer mientras carga', (tester) async {
+    final busqueda = _BusquedaCargando();
+    addTearDown(busqueda.dispose);
+
+    await tester.pumpWidget(
+      ListenableProvider<EstadoBusqueda>.value(
+        value: busqueda,
+        child: MaterialApp(
+          locale: const Locale('es'),
+          localizationsDelegates: AppLocalizations.localizationsDelegates,
+          supportedLocales: AppLocalizations.supportedLocales,
+          home: const Scaffold(body: PantallaBuscar()),
+        ),
+      ),
+    );
+    await tester.pump();
+
+    expect(find.byType(TarjetaEmisoraShimmer), findsWidgets);
+    expect(find.byType(CircularProgressIndicator), findsNothing);
+  });
+}

test/pantallas/pantalla_favoritos_plural_test.dart

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+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pluriwave/l10n/gen/app_localizations.dart';
+
+/// S5-R5: bare counters must use proper ARB plural messages.
+void main() {
+  test('stationCount cambia entre singular y plural (en)', () async {
+    final l10n = await AppLocalizations.delegate.load(const Locale('en'));
+
+    expect(l10n.stationCount(1), '1 station');
+    expect(l10n.stationCount(5), '5 stations');
+  });
+
+  test('stationCount cambia entre singular y plural (es)', () async {
+    final l10n = await AppLocalizations.delegate.load(const Locale('es'));
+
+    expect(l10n.stationCount(1), isNot(l10n.stationCount(5)));
+    expect(l10n.stationCount(5), contains('5'));
+  });
+}

test/tema/notification_color_test.dart

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+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pluriwave/main.dart';
+import 'package:pluriwave/tema/pluriwave_tokens.dart';
+
+/// S5-R8: the audio notification accent is the PluriWave brand color,
+/// not the M3 default purple.
+void main() {
+  test('AudioServiceConfig usa el color de marca', () {
+    expect(configuracionAudioService.notificationColor, PluriWaveTokens.brand);
+    expect(
+      configuracionAudioService.notificationColor,
+      isNot(const Color(0xFF6750A4)),
+    );
+  });
+}

test/tema/pluri_animate_test.dart

@@ -0,0 +1,78 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_animate/flutter_animate.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pluriwave/tema/pluri_animate.dart';
+
+/// S5-R3: the central reduced-motion gate. When the OS reports
+/// disableAnimations, the helpers must return the child UNANIMATED
+/// (no [Animate] wrapper at all).
+void main() {
+  Widget host({required bool reducedMotion, required WidgetBuilder builder}) {
+    return MediaQuery(
+      data: MediaQueryData(disableAnimations: reducedMotion),
+      child: Directionality(
+        textDirection: TextDirection.ltr,
+        child: Builder(builder: builder),
+      ),
+    );
+  }
+
+  testWidgets('pluriFadeIn anima en modo normal', (tester) async {
+    await tester.pumpWidget(
+      host(
+        reducedMotion: false,
+        builder: (context) => const Text('hola').pluriFadeIn(context),
+      ),
+    );
+    expect(find.byType(Animate), findsOneWidget);
+    await tester.pumpAndSettle();
+  });
+
+  testWidgets('pluriFadeIn devuelve el hijo intacto con reduced motion', (
+    tester,
+  ) async {
+    await tester.pumpWidget(
+      host(
+        reducedMotion: true,
+        builder: (context) => const Text('hola').pluriFadeIn(context),
+      ),
+    );
+    expect(find.byType(Animate), findsNothing);
+    expect(find.text('hola'), findsOneWidget);
+  });
+
+  testWidgets('pluriFadeSlideIn respeta el gate de reduced motion', (
+    tester,
+  ) async {
+    await tester.pumpWidget(
+      host(
+        reducedMotion: true,
+        builder:
+            (context) =>
+                const Text('hola').pluriFadeSlideIn(context, beginY: 0.2),
+      ),
+    );
+    expect(find.byType(Animate), findsNothing);
+
+    await tester.pumpWidget(
+      host(
+        reducedMotion: false,
+        builder:
+            (context) =>
+                const Text('hola').pluriFadeSlideIn(context, beginY: 0.2),
+      ),
+    );
+    expect(find.byType(Animate), findsOneWidget);
+    await tester.pumpAndSettle();
+  });
+
+  testWidgets('pluriScaleIn respeta el gate de reduced motion', (tester) async {
+    await tester.pumpWidget(
+      host(
+        reducedMotion: true,
+        builder: (context) => const Text('hola').pluriScaleIn(context),
+      ),
+    );
+    expect(find.byType(Animate), findsNothing);
+  });
+}

test/widgets/tarjeta_emisora_a11y_test.dart

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+import 'dart:ui' show Tristate;
+
+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/widgets/tarjeta_emisora.dart';
+import 'package:provider/provider.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import '../helpers/fakes.dart';
+
+/// S5-R2: the mini favorite button in the full card must be accessible
+/// (semantic button with label + toggled state) and reach a 48dp target.
+void main() {
+  setUp(() {
+    SharedPreferences.setMockInitialValues({});
+  });
+
+  testWidgets('el favorito mini es accesible y mide al menos 48x48 dp', (
+    tester,
+  ) async {
+    final semantics = tester.ensureSemantics();
+    final estado = EstadoRadio(
+      audio: FakeServicioAudio(),
+      favoritos: FakeServicioFavoritos(),
+      radio: FakeServicioRadio(),
+      servicioEcualizador: FakeServicioEcualizador(),
+      iniciarAutomaticamente: false,
+    );
+    addTearDown(estado.dispose);
+
+    await tester.pumpWidget(
+      ChangeNotifierProvider<EstadoRadio>.value(
+        value: estado,
+        child: MaterialApp(
+          locale: const Locale('es'),
+          localizationsDelegates: AppLocalizations.localizationsDelegates,
+          supportedLocales: AppLocalizations.supportedLocales,
+          home: Scaffold(
+            body: Center(
+              child: SizedBox(
+                width: 220,
+                height: 300,
+                // Full (non-compact) card: it renders the MINI favorite.
+                child: TarjetaEmisora(
+                  emisora: emisoraDemo(uuid: 'a11y-1', nombre: 'A11y FM'),
+                ),
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+    await tester.pump();
+
+    final l10n = await AppLocalizations.delegate.load(const Locale('es'));
+
+    // Semantic node: button + label (favorite is OFF, so the "add" label).
+    final boton = find.bySemanticsLabel(l10n.favoritesAddTooltip);
+    expect(boton, findsOneWidget);
+    final nodo = tester.getSemantics(boton);
+    final flags = nodo.flagsCollection;
+    expect(flags.isButton, isTrue);
+    // Toggled state present (favorite OFF) — tristate: not null, not true.
+    expect(flags.isToggled, Tristate.isFalse);
+
+    // Touch target: at least 48x48 dp (S5-R2-A).
+    final size = tester.getSize(boton);
+    expect(size.width, greaterThanOrEqualTo(48));
+    expect(size.height, greaterThanOrEqualTo(48));
+
+    semantics.dispose();
+  });
+}