fix(alarm): unfreeze snooze modal and add per-minute snooze countdown

The snooze button was fire-and-forget without error handling: if
posponerAlarma threw (e.g. native scheduleAlarm returns false on a
device without exact-alarm permission), _dismissScreen never ran. The
stuck modal also kept _alarmaSonandoActiva true, which made the next
ring get ignored. _posponer/_detener now dismiss in a finally and stop
audio defensively.

Add a native, AlarmManager-driven snooze countdown notification that
re-posts every minute ("Rings in N min", 3->2->1) while the engine is
dead. scheduleSpec drives scheduleSnoozeCountdown for snoozes (instead
of the 30-min pre-notice). Localized text and button labels travel
Dart->Kotlin as {minutes} templates, same pattern as preNoticeTemplate.

Notification actions: "snooze again" (snoozeAgain, anchored to now)
reports back via the existing snoozed event; "stop" (cancelSnooze)
records a handled occurrence for cold-start reconciliation and emits a
new snoozeCancelled event handled in EstadoAlarmas.

Adds snoozeCountdown/snoozeAgainAction keys across all 13 locales and a
test for the snoozeCancelled event. Kotlin changes are static-reviewed
only; no Android build environment available here.

test/estado/estado_alarmas_snooze_test.dart

@@ -248,4 +248,61 @@ void main() {
       expect(android.programadas.last.snoozeHasta, isNull);
     },
   );
+
+  test(
+    'evento nativo snoozeCancelled limpia el snooze y avanza sin reprogramar',
+    () async {
+      final ahora = DateTime(2026, 6, 11, 7, 32);
+      final android = FakePuertoAlarmasAndroid();
+      final estado = EstadoAlarmas(
+        servicio: ServicioAlarmas(reloj: () => ahora),
+        android: android,
+        iniciarAutomaticamente: false,
+      );
+      addTearDown(estado.dispose);
+      addTearDown(android.dispose);
+      await estado.guardarAlarma(
+        AlarmaMusical(
+          id: 'cancel1',
+          nombre: 'Diaria',
+          hora: 7,
+          minuto: 30,
+          tipoProgramacion: TipoProgramacionAlarma.diaria,
+          diasSemana: const [],
+          proximaEjecucion: DateTime(2026, 6, 11, 7, 30),
+          snoozeHasta: DateTime(2026, 6, 11, 7, 35),
+          snoozeOrigen: DateTime(2026, 6, 11, 7, 30),
+        ),
+      );
+      expect(estado.alarmas.single.snoozeHasta, isNotNull);
+      final programadasAntes = android.programadas.length;
+      final notificado = Completer<void>();
+      estado.addListener(() {
+        if (!notificado.isCompleted) notificado.complete();
+      });
+
+      android.emitirEvento(
+        EventoAlarmaAndroid(
+          alarmaId: 'cancel1',
+          titulo: 'Diaria',
+          accion: EventoAlarmaAndroid.accionSnoozeCancelled,
+          occurrenceAtMillis:
+              DateTime(2026, 6, 11, 7, 30).millisecondsSinceEpoch,
+        ),
+      );
+      await notificado.future;
+
+      expect(estado.alarmas.single.snoozeHasta, isNull);
+      expect(
+        estado.alarmas.single.proximaEjecucion,
+        DateTime(2026, 6, 12, 7, 30),
+        reason: 'avanza a la próxima ocurrencia diaria',
+      );
+      expect(
+        android.programadas.length,
+        programadasAntes,
+        reason: 'el nativo ya reprogramó; no debe haber un segundo programar',
+      );
+    },
+  );
 }