feat(eq): android auto custom equalizer and robust device detection

- MainActivity: onListen re-emits the current active device and registers
  the audio device callback idempotently, so recreated activities resync
  instead of freezing the active-device id on a disconnected device.
- servicio_dispositivo_audio: resubscribir() re-opens the event channel;
  estado_ecualizador exposes refrescarDispositivoActual() with an
  in-flight guard, invoked on app resume and when opening advanced EQ
  options, clearing stale green-dot device selections.
- navegacion_auto/servicio_audio: new 'Personalizado' browse tree in
  Android Auto (5 band folders, 13 gain steps each) applied live via
  setBanda; preset and gain taps persist at device level when
  multi-device EQ is active and respect station/matrix overrides,
  with apply-before-persist ordering and children-changed notifications.
- l10n: regenerate stale generated localizations; add rxdart as direct
  dependency for the subscribeToChildren override.

test/helpers/fakes.dart

@@ -433,11 +433,20 @@ class FakeServicioDispositivoAudioThrows extends ServicioDispositivoAudio {
   @override
   Stream<DispositivoAudio> get onDispositivoCambiado => _controller.stream;
 
+  /// Number of times [resubscribir] was called.
+  int resubscribirLlamadas = 0;
+
   @override
   Future<DispositivoAudio> obtenerDispositivoActual() async {
     throw Exception('Platform channel error: device unavailable');
   }
 
+  @override
+  Future<void> resubscribir() async {
+    resubscribirLlamadas++;
+    throw Exception('Platform channel error: resubscribe unavailable');
+  }
+
   @override
   Future<bool> solicitarPermisoBluetooth() async => true;
 
@@ -462,6 +471,9 @@ class FakeServicioDispositivoAudio extends ServicioDispositivoAudio {
   /// Number of times [solicitarPermisoBluetooth] was called.
   int solicitarPermisoBluetoothCalls = 0;
 
+  /// Number of times [resubscribir] was called.
+  int resubscribirLlamadas = 0;
+
   final _controller = StreamController<DispositivoAudio>.broadcast();
   DispositivoAudio? _dispositivoActual;
 
@@ -481,6 +493,11 @@ class FakeServicioDispositivoAudio extends ServicioDispositivoAudio {
         );
   }
 
+  @override
+  Future<void> resubscribir() async {
+    resubscribirLlamadas++;
+  }
+
   @override
   Future<bool> solicitarPermisoBluetooth() async {
     solicitarPermisoBluetoothCalls++;
@@ -493,6 +510,14 @@ class FakeServicioDispositivoAudio extends ServicioDispositivoAudio {
     _controller.add(dispositivo);
   }
 
+  /// Helper for tests: change the cached device WITHOUT emitting a stream
+  /// event — simulates the stale-subscription bug (activity recreation),
+  /// where the native device changed but the event never reached Dart and
+  /// only a fresh query ([obtenerDispositivoActual]) sees the new value.
+  void establecerDispositivoSinEvento(DispositivoAudio dispositivo) {
+    _dispositivoActual = dispositivo;
+  }
+
   @override
   Future<void> dispose() async {
     await _controller.close();