feat(alarmas): replace one-line reliability button with full diagnostics screen

Surface all six DiagnosticoAlarmasAndroid fields instead of three: the
battery-optimization exemption and native pending-alarm count were
already collected but silently dropped by the old widget. Each failing
signal now offers a "Fix this" action that opens the right system
settings screen (exact alarms, notifications, full-screen intent,
battery optimization), guarded by SDK level and never crashing when a
ROM lacks that screen. Manufacturers known for aggressive background
killing (Xiaomi/Redmi/POCO, Huawei, Oppo, Vivo, OnePlus, Samsung) get
an honest explanation that Autostart must be enabled manually, since
there is no API to detect or grant it.

Notifications now deep-links straight to
ACTION_APP_NOTIFICATION_SETTINGS via a new openNotificationSettings
native method, instead of reusing the runtime permission popup meant
for first-time alarm creation.

New copy is added to all 13 ARB locales with real per-language
translations (not Spanish copies), verified by the ARB parity and
anti-copy tests plus the corruption scanner.

lib/servicios/servicio_alarmas_android.dart

@@ -190,6 +190,15 @@ abstract class PuertoAlarmasAndroid {
   Future<bool> solicitarPermisoPantallaCompleta();
   Future<bool> solicitarExencionBateria();
 
+  /// Opens the system's per-app notification settings screen directly
+  /// (`ACTION_APP_NOTIFICATION_SETTINGS`), as opposed to
+  /// [solicitarPermisoNotificaciones]'s runtime permission popup. Used from
+  /// the reliability diagnostics screen: once a user is troubleshooting an
+  /// alarm that already failed, sending them straight to Settings is more
+  /// robust than a runtime dialog the OS may refuse to show again after a
+  /// prior denial.
+  Future<bool> abrirConfiguracionNotificaciones();
+
   Future<DiagnosticoAlarmasAndroid> diagnostico();
   Future<EventoAlarmaAndroid?> obtenerEventoInicial();
   Future<List<EjecucionAlarmaNativa>> obtenerEjecucionesNativasGestionadas();
@@ -416,6 +425,14 @@ class ServicioAlarmasAndroid implements PuertoAlarmasAndroid {
     return abierto ?? false;
   }
 
+  @override
+  Future<bool> abrirConfiguracionNotificaciones() async {
+    final abierto = await _channel.invokeMethod<bool>(
+      'openNotificationSettings',
+    );
+    return abierto ?? false;
+  }
+
   @override
   Future<DiagnosticoAlarmasAndroid> diagnostico() async {
     debugPrint('[PluriWave][alarmas] diagnostico android');