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.

android/app/src/main/kotlin/es/freetimelab/pluriwave/MainActivity.kt

@@ -1014,6 +1014,15 @@ class MainActivity : AudioServiceActivity() {
                 override fun onListen(arguments: Any?, events: EventChannel.EventSink?) {
                     audioDevicesSink = events
                     registerAudioDeviceCallback()
+                    // Immediate resync: emit the current active device on every
+                    // (re)subscription. The Flutter engine outlives the Activity
+                    // (AudioServiceActivity), so a recreated Activity installs a
+                    // fresh StreamHandler that never sees a "listen" until Dart
+                    // resubscribes — without this emission the Dart side would
+                    // keep a stale device until the next physical connect event.
+                    val device = getActiveAudioDevice()
+                    Log.d(tag, "audio_devices.onListen -> $device")
+                    events?.success(device)
                 }
 
                 override fun onCancel(arguments: Any?) {
@@ -1041,6 +1050,9 @@ class MainActivity : AudioServiceActivity() {
     private fun registerAudioDeviceCallback() {
         if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) return
         val audioManager = getSystemService(Context.AUDIO_SERVICE) as AudioManager
+        // Idempotent: a re-listen without a prior cancel must not leak the
+        // previously registered callback.
+        audioDeviceCallback?.let { audioManager.unregisterAudioDeviceCallback(it) }
         val callback = object : AudioDeviceCallback() {
             override fun onAudioDevicesAdded(addedDevices: Array<out AudioDeviceInfo>) {
                 // Emit the current active output device when something connects.