feat(alarms): native reliability fixes and end-to-end snooze

- Use mediaPlayback|systemExempted FGS type with FOREGROUND_SERVICE_SYSTEM_EXEMPTED so alarms fire on Android 14+ (FOREGROUND_SERVICE_ALARM does not exist in the SDK)
- Deduplicate fire notifications: the foreground service FSI notification is the single owner; receiver path removed
- Notification channel v2 with alarm sound URI and USAGE_ALARM attributes, one-time guarded migration from legacy channels
- Pass fallback station through the MethodChannel (NativeAlarmSpec schemaVersion 3) with a three-stage audio chain: primary -> fallback station -> bundled WAV
- Native fade-in volume ramp honoring fadeInSegundos when the app is killed
- Request battery-optimization exemption once, tracked with a persisted asked-once flag
- Fix snooze end-to-end: native ACTION_SNOOZE now reports back to Flutter (snoozed event + cold-start sync), snooze anchor unified to occurrence+minutes on both sides, periodic recalc no longer erases an active snooze
- Add snooze buttons (3/5/10/custom) to the ringing screen with shared audio teardown
- Redesign ringing screen on PluriWaveScaffold with reduced-motion-aware entry animation (new PluriAnimate helper)
- Alarm editor: live next-trigger preview, searchable station pickers (primary and fallback), configurable snooze duration, volume floor down to 0
- New alarm strings localized across all 13 locales
- New unit/widget tests for the snooze flow, alarm bridge payloads, ringing screen and editor (77 tests green)
- SDD artifacts for the app-quality-and-native-alarms change (explore, proposal, spec, design, tasks, apply progress)

test/helpers/fakes.dart

@@ -18,6 +18,8 @@ class FakeServicioAudio extends ServicioAudio {
   final List<PresetEcualizador> presetsAplicados = [];
   final List<Emisora> emisorasReproducidas = [];
   final List<bool> cambiosEcualizadorActivo = [];
+  final List<double> volumenesAplicados = [];
+  int pausas = 0;
   Emisora? _emisoraActual;
   EstadoReproduccion _estadoActual = EstadoReproduccion.detenido;
 
@@ -46,6 +48,17 @@ class FakeServicioAudio extends ServicioAudio {
     emitirEstado(EstadoReproduccion.detenido);
   }
 
+  @override
+  Future<void> pausar() async {
+    pausas++;
+    emitirEstado(EstadoReproduccion.pausado);
+  }
+
+  @override
+  Future<void> setVolumen(double vol) async {
+    volumenesAplicados.add(vol);
+  }
+
   void emitirEstado(EstadoReproduccion estado) {
     _estadoActual = estado;
     _estadoController.add(estado);
@@ -116,7 +129,8 @@ class FakeServicioFavoritos extends ServicioFavoritos {
   }
 
   @override
-  Future<List<GrupoFavoritos>> obtenerGrupos() async => List.unmodifiable(_grupos);
+  Future<List<GrupoFavoritos>> obtenerGrupos() async =>
+      List.unmodifiable(_grupos);
 
   @override
   Future<GrupoFavoritos> crearGrupo(String nombre) async {
@@ -151,9 +165,10 @@ class FakeServicioFavoritos extends ServicioFavoritos {
 
   @override
   Future<void> asignarGrupo(String uuid, String grupoId) async {
-    final destino = _grupos.any((g) => g.id == grupoId)
-        ? grupoId
-        : GrupoFavoritos.sinAsignarId;
+    final destino =
+        _grupos.any((g) => g.id == grupoId)
+            ? grupoId
+            : GrupoFavoritos.sinAsignarId;
     final index = _favoritos.indexWhere((e) => e.uuid == uuid);
     if (index != -1) {
       _favoritos[index] = _favoritos[index].copyWith(grupoFavoritosId: destino);

test/helpers/fakes_alarmas.dart

@@ -0,0 +1,106 @@
+import 'dart:async';
+
+import 'package:pluriwave/modelos/alarma_musical.dart';
+import 'package:pluriwave/servicios/servicio_alarmas_android.dart';
+import 'package:pluriwave/servicios/servicio_grabacion_radio.dart';
+
+/// Shared fake of the Android alarm bridge for alarm-related tests.
+class FakePuertoAlarmasAndroid implements PuertoAlarmasAndroid {
+  final programadas = <AlarmaMusical>[];
+  final canceladas = <String>[];
+  final detenidas = <String>[];
+  final ocultadas = <String>[];
+  final ejecucionesNativas = <EjecucionAlarmaNativa>[];
+  final snoozesNativos = <EstadoSnoozeNativo>[];
+  final _eventos = StreamController<EventoAlarmaAndroid>.broadcast();
+  bool ignoraOptimizacionBateria = true;
+  int solicitudesExencionBateria = 0;
+
+  /// Simulates a native -> Flutter `alarmFired` MethodChannel event.
+  void emitirEvento(EventoAlarmaAndroid evento) => _eventos.add(evento);
+
+  @override
+  Stream<EventoAlarmaAndroid> get eventosAlarma => _eventos.stream;
+
+  @override
+  Future<void> programar(AlarmaMusical alarma) async {
+    programadas.add(alarma);
+  }
+
+  @override
+  Future<void> cancelar(String alarmaId) async {
+    canceladas.add(alarmaId);
+  }
+
+  @override
+  Future<void> detenerSonidoNativo(String alarmaId) async {
+    detenidas.add(alarmaId);
+  }
+
+  @override
+  Future<void> ocultarNotificacionAlarma(String alarmaId) async {
+    ocultadas.add(alarmaId);
+  }
+
+  @override
+  Future<void> confirmarAudioFlutter(String alarmaId) async {
+    detenidas.add(alarmaId);
+  }
+
+  @override
+  Future<DiagnosticoAlarmasAndroid> diagnostico() async =>
+      DiagnosticoAlarmasAndroid(
+        puedeProgramarExactas: true,
+        notificacionesPermitidas: true,
+        puedeUsarPantallaCompleta: true,
+        ignoraOptimizacionBateria: ignoraOptimizacionBateria,
+        alarmasNativasPendientes: 0,
+        fabricante: 'test',
+        versionSdk: 35,
+      );
+
+  @override
+  Future<bool> solicitarExencionBateria() async {
+    solicitudesExencionBateria++;
+    return true;
+  }
+
+  @override
+  Future<EventoAlarmaAndroid?> obtenerEventoInicial() async => null;
+
+  @override
+  Future<List<EjecucionAlarmaNativa>>
+  obtenerEjecucionesNativasGestionadas() async => ejecucionesNativas;
+
+  @override
+  Future<List<EstadoSnoozeNativo>> obtenerEstadoSnoozeNativo() async =>
+      List.of(snoozesNativos);
+
+  @override
+  Future<bool> solicitarPermisoAlarmasExactas() async => true;
+
+  @override
+  Future<bool> solicitarPermisoNotificaciones() async => true;
+
+  @override
+  Future<bool> solicitarPermisoPantallaCompleta() async => true;
+
+  Future<void> dispose() => _eventos.close();
+}
+
+/// Inactive recording service fake, safe for widget tests.
+class FakeServicioGrabacionRadioInactiva extends ServicioGrabacionRadio {
+  final _controller = StreamController<EstadoGrabacionRadio>.broadcast();
+
+  @override
+  EstadoGrabacionRadio get estado => const EstadoGrabacionRadio.inactiva();
+
+  @override
+  Stream<EstadoGrabacionRadio> get estadoStream => _controller.stream;
+
+  @override
+  Future<void> inicializar() async {}
+
+  @override
+  Future<void> dispose() => _controller.close();
+}