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/servicios/servicio_dispositivo_audio.dart

@@ -4,6 +4,14 @@ import 'package:flutter/services.dart';
 
 import '../modelos/dispositivo_audio.dart';
 
+/// Composite-placeholder id prefix (bt-device-identity ADR-6): marks a BT
+/// device whose real MAC is not yet known (BLUETOOTH_CONNECT denied or
+/// unresolved). Single source of truth for the marker shared by
+/// `EstadoEcualizador` and the Auto EQ persistence-targeting logic: ids with
+/// this prefix are transient and must never receive a device-level preset
+/// entry.
+const prefijoPlaceholderBtName = 'bt_a2dp:name:';
+
 /// Abstract service for audio device detection.
 ///
 /// Implementations:
@@ -21,6 +29,16 @@ abstract class ServicioDispositivoAudio {
   /// (method channel round-trip). Returns the cached value if already known.
   Future<DispositivoAudio> obtenerDispositivoActual();
 
+  /// Cancels the current device-change subscription and subscribes again.
+  ///
+  /// Sends the platform `cancel`+`listen` control messages, which re-triggers
+  /// `onListen` on the CURRENT activity's stream handler and re-registers the
+  /// native `AudioDeviceCallback`. Needed because the Flutter engine outlives
+  /// the Activity (`AudioServiceActivity`): after an activity recreation the
+  /// new handler never saw a `listen`, so its event sink stays null and
+  /// device events stop reaching Dart until this resync runs.
+  Future<void> resubscribir();
+
   /// Requests the `BLUETOOTH_CONNECT` runtime permission (API 31+) at the
   /// point the device-management UI is opened (bt-device-identity ADR-1).
   /// Returns true when granted or not required (SDK < 31, iOS); false when
@@ -88,6 +106,12 @@ class ServicioDispositivoAudioReal extends ServicioDispositivoAudio {
     return device;
   }
 
+  @override
+  Future<void> resubscribir() async {
+    await _eventSub?.cancel();
+    _subscribeToEvents();
+  }
+
   @override
   Future<bool> solicitarPermisoBluetooth() async {
     final granted = await _methodChannel.invokeMethod<bool>(
@@ -102,6 +126,15 @@ class ServicioDispositivoAudioReal extends ServicioDispositivoAudio {
     await _controller.close();
   }
 
+  /// Builds a [DispositivoAudio] from the raw platform-channel map shape.
+  ///
+  /// Public so headless consumers (the Android Auto handler's one-shot
+  /// `getActiveDevice` query) reuse the exact same mapping without opening a
+  /// second event-channel subscription, which would steal this service's
+  /// stream handler on the Dart side.
+  static DispositivoAudio dispositivoDesdeMapa(Map<String, dynamic> map) =>
+      _mapToDispositivo(map);
+
   static DispositivoAudio _mapToDispositivo(Map<String, dynamic> map) {
     final id = map['id'] as String? ?? 'builtin_speaker';
     final type = map['type'] as int? ?? 2;