feat(alarm): complete musical alarm flows

lib/servicios/servicio_alarmas_android.dart

@@ -1,7 +1,29 @@
+import 'dart:async';
+
 import 'package:flutter/services.dart';
 
 import '../modelos/alarma_musical.dart';
 
+class EventoAlarmaAndroid {
+  const EventoAlarmaAndroid({
+    required this.alarmaId,
+    required this.titulo,
+    required this.accion,
+  });
+
+  final String alarmaId;
+  final String titulo;
+  final String accion;
+
+  factory EventoAlarmaAndroid.fromMap(Map<Object?, Object?> map) {
+    return EventoAlarmaAndroid(
+      alarmaId: map['alarmId'] as String? ?? '',
+      titulo: map['alarmTitle'] as String? ?? 'PluriWave',
+      accion: map['alarmAction'] as String? ?? '',
+    );
+  }
+}
+
 class DiagnosticoAlarmasAndroid {
   const DiagnosticoAlarmasAndroid({
     required this.puedeProgramarExactas,
@@ -28,9 +50,16 @@ class DiagnosticoAlarmasAndroid {
 class ServicioAlarmasAndroid {
   ServicioAlarmasAndroid({
     MethodChannel channel = const MethodChannel('pluriwave/alarm_scheduler'),
-  }) : _channel = channel;
+  }) : _channel = channel {
+    _instalarHandler(_channel);
+  }
 
   final MethodChannel _channel;
+  static final _eventosController =
+      StreamController<EventoAlarmaAndroid>.broadcast();
+  static bool _handlerInstalado = false;
+
+  Stream<EventoAlarmaAndroid> get eventosAlarma => _eventosController.stream;
 
   Future<void> programar(AlarmaMusical alarma) async {
     final proxima = alarma.proximaEjecucion;
@@ -56,4 +85,28 @@ class ServicioAlarmasAndroid {
     );
     return DiagnosticoAlarmasAndroid.fromMap(raw ?? const {});
   }
+
+  Future<EventoAlarmaAndroid?> obtenerEventoInicial() async {
+    final raw = await _channel.invokeMethod<Map<Object?, Object?>>(
+      'getInitialAlarmIntent',
+    );
+    if (raw == null || raw.isEmpty) return null;
+    final evento = EventoAlarmaAndroid.fromMap(raw);
+    return evento.alarmaId.isEmpty ? null : evento;
+  }
+
+  static void _instalarHandler(MethodChannel channel) {
+    if (_handlerInstalado) return;
+    _handlerInstalado = true;
+    channel.setMethodCallHandler((call) async {
+      if (call.method != 'alarmFired') return;
+      final args = call.arguments;
+      if (args is Map) {
+        final evento = EventoAlarmaAndroid.fromMap(args);
+        if (evento.alarmaId.isNotEmpty) {
+          _eventosController.add(evento);
+        }
+      }
+    });
+  }
 }