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.

lib/estado/estado_ecualizador.dart

@@ -26,12 +26,6 @@ import '../servicios/servicio_ecualizador.dart';
 /// When the toggle is false, resolution falls back to the original 2-level
 /// hierarchy (station → global) — zero behavioral change vs. prior releases.
 class EstadoEcualizador extends ChangeNotifier {
-  /// Composite-placeholder id prefix (bt-device-identity ADR-6): marks a
-  /// device whose real Bluetooth MAC is not yet known (BLUETOOTH_CONNECT
-  /// denied or unresolved). Devices with this prefix still update the
-  /// platform-name cache but never auto-create a `presetsDispositivo` entry.
-  static const _prefijoPlaceholderCompuesto = 'bt_a2dp:name:';
-
   EstadoEcualizador({
     required this.audio,
     ServicioEcualizador? servicio,
@@ -73,6 +67,7 @@ class EstadoEcualizador extends ChangeNotifier {
   bool _eqMultiDeviceEnabled = false;
   String? _dispositivoActualId;
   StreamSubscription<DispositivoAudio>? _deviceSub;
+  Future<void>? _refrescoEnCurso;
 
   PresetEcualizador get presetActual => _presetActual;
   PresetEcualizador get presetPrincipal => _presetPrincipal;
@@ -208,6 +203,38 @@ class EstadoEcualizador extends ChangeNotifier {
     }
   }
 
+  /// Re-syncs the active device after a possibly-missed native resync
+  /// (activity recreation over the cached engine, return to foreground,
+  /// opening the settings section): re-subscribes the platform event channel
+  /// via [ServicioDispositivoAudio.resubscribir] — re-registering the native
+  /// callback on the CURRENT activity — and re-seeds [_dispositivoActualId]
+  /// with a fresh query. No-op when the multi-device toggle is off or no
+  /// device service is injected; safe to call repeatedly. Concurrent calls
+  /// (app-resume observer + settings initState) share the same in-flight
+  /// refresh instead of racing [ServicioDispositivoAudio.resubscribir],
+  /// which would leak a native AudioDeviceCallback.
+  Future<void> refrescarDispositivoActual() {
+    final enCurso = _refrescoEnCurso;
+    if (enCurso != null) return enCurso;
+    final refresco = _refrescarDispositivoActual().whenComplete(() {
+      _refrescoEnCurso = null;
+    });
+    _refrescoEnCurso = refresco;
+    return refresco;
+  }
+
+  Future<void> _refrescarDispositivoActual() async {
+    if (!_eqMultiDeviceEnabled) return;
+    final svc = _dispositivoAudio;
+    if (svc == null) return;
+    try {
+      await svc.resubscribir();
+    } catch (_) {
+      // A failed resubscribe must never block the fresh-query re-seed below.
+    }
+    await _sembrarDispositivoActual();
+  }
+
   /// Subscribes to the device change stream if multi-device is enabled.
   void _configurarSuscripcionDispositivo() {
     _deviceSub?.cancel();
@@ -239,7 +266,7 @@ class EstadoEcualizador extends ChangeNotifier {
     // resolves to the eventual real-MAC id.
     final esBase = dispositivo.tipo == TipoDispositivo.altavozInterno;
     final esPlaceholderCompuesto = dispositivo.id.startsWith(
-      _prefijoPlaceholderCompuesto,
+      prefijoPlaceholderBtName,
     );
     if (!esBase &&
         !esPlaceholderCompuesto &&