refactor(auto): drop the in-car equalizer, keep EQ on the phone

The car tree carried a whole equalizer feature: an `Ecualizador` root folder
with the six factory presets, a browsable `Personalizado` folder, five band
folders and thirteen gain leaves each, plus the media-id namespaces, routing
predicates, persistence-targeting and children-changed plumbing that fed
them. Equalization is a phone task; the driver should not be tuning 5 bands
from a car screen.

Removed: the `eq_preset:`/`eq_banda:`/`eq_gain:` namespaces and their
predicates and parsers, the `ecualizador`/`eq_custom` folder ids and their
getChildren branches, itemPresetEq/presetsEq/itemEqPersonalizado/bandasEq/
gananciasBandaEq, resolverPresetEq, presetPersonalizadoEfectivo,
dispositivoDestinoEq, debeAplicarPrincipalAhora/debeAplicarSeleccionAhora,
aplicarPresetPorMediaId, aplicarGananciaPorMediaId, and in the handler the
playFromMediaId branches, _presetPersonalizadoAuto, _dispositivoActivoAuto,
_dispositivoDestinoEqAuto and the subscribeToChildren/_hijosSubjects
notification machinery that existed only to refresh band titles after a gain
tap.

Deliberately KEPT: automatic per-device EQ. Reaching the car still applies
that device's preset, because that lives in EstadoEcualizador and the
output-device detection, not in this tree — it works with Android Auto or
without it. Configuring is what moves to the phone; applying stays automatic.

Also kept: the `eq_preset_*_v1` SharedPreferences keys in
ServicioEcualizador, which share a name with the deleted media-id prefix by
coincidence only and hold the phone's own presets.

The root folder set goes from five entries to four (three without local
music); its test now asserts no equalizer folder is offered at all, so a
reintroduction has to be deliberate.

lib/servicios/servicio_audio.dart

@@ -4,13 +4,10 @@ import 'dart:ui' show Locale;
 
 import 'package:audio_service/audio_service.dart';
 import 'package:flutter/foundation.dart' show visibleForTesting;
-import 'package:flutter/services.dart' show MethodChannel;
 import 'package:just_audio/just_audio.dart';
-import 'package:rxdart/rxdart.dart' show BehaviorSubject, ValueStream;
 
 import '../l10n/display_names.dart';
 import '../l10n/gen/app_localizations.dart';
-import '../modelos/dispositivo_audio.dart';
 import '../modelos/emisora.dart';
 import '../modelos/pista_local.dart';
 import '../modelos/preset_ecualizador.dart';
@@ -19,8 +16,6 @@ import 'controlador_reconexion.dart';
 import 'musica_local_auto.dart';
 import 'navegacion_auto.dart';
 import 'servicio_audio_session.dart';
-import 'servicio_dispositivo_audio.dart';
-import 'servicio_ecualizador.dart';
 
 /// Estado de reproducción expuesto al UI.
 enum EstadoReproduccion {
@@ -494,7 +489,7 @@ class PluriWaveAudioHandler extends BaseAudioHandler
   }
 
   /// Public entry point for EVERY external play (phone `reproducir`, car
-  /// `emisora:`/`grupo:`/`pista:`/`eq_preset:` non-path). ALWAYS clears the
+  /// `emisora:`/`grupo:`/`pista:` non-path). ALWAYS clears the
   /// local queue FIRST (Design ADR-2, the single load-bearing invariant:
   /// "external play = leave queue mode") so a stale auto-advance can never
   /// fire after an external source switch, then delegates to the private
@@ -913,10 +908,6 @@ class PluriWaveAudioHandler extends BaseAudioHandler
     await _androidAudioSessionIdSub?.cancel();
     await _player.dispose();
     await _androidAudioSessionIdController.close();
-    for (final subject in _hijosSubjects.values) {
-      await subject.close();
-    }
-    _hijosSubjects.clear();
   }
 
   Emisora _emisoraDesdeMediaItem(MediaItem mediaItem) {
@@ -937,88 +928,6 @@ class PluriWaveAudioHandler extends BaseAudioHandler
   /// method channel `ServicioDispositivoAudioReal` talks to, but method
   /// calls only — opening a second EventChannel subscription here would
   /// steal the phone-side service's Dart stream handler.
-  static const _canalDispositivos = MethodChannel('pluriwave/audio_devices');
-
-  /// Short timeout for the device query: on a headless Auto bind no
-  /// Activity (and thus no channel handler) exists, and a car tap must fall
-  /// back to global persistence instead of hanging.
-  static const _timeoutConsultaDispositivo = Duration(seconds: 2);
-
-  /// Fresh active-output-device query for the car EQ paths. Returns `null`
-  /// on ANY failure (missing handler while headless, timeout, malformed
-  /// map) so callers degrade to global persistence — never a crash.
-  Future<DispositivoAudio?> _dispositivoActivoAuto() async {
-    try {
-      final raw = await _canalDispositivos
-          .invokeMethod<Map<dynamic, dynamic>>('getActiveDevice')
-          .timeout(_timeoutConsultaDispositivo);
-      if (raw == null) return null;
-      return ServicioDispositivoAudioReal.dispositivoDesdeMapa(
-        Map<String, dynamic>.from(raw),
-      );
-    } catch (_) {
-      return null;
-    }
-  }
-
-  /// Resolves the persistence target for a car EQ action (feature
-  /// auto-custom-eq): a deviceId for a DEVICE-level write, `null` for the
-  /// global principal (toggle off, built-in speaker, placeholder id, or the
-  /// headless error/timeout fallback).
-  Future<String?> _dispositivoDestinoEqAuto(
-    ServicioEcualizador servicio,
-  ) async {
-    try {
-      final config = await servicio.cargar();
-      if (!config.eqMultiDeviceEnabled) return null;
-      return dispositivoDestinoEq(
-        multiDeviceEnabled: config.eqMultiDeviceEnabled,
-        dispositivo: await _dispositivoActivoAuto(),
-      );
-    } catch (_) {
-      return null;
-    }
-  }
-
-  /// The custom preset the Auto tree shows and edits right now (feature
-  /// auto-custom-eq): the device-level entry for the current output device
-  /// when multi-device is on, the global principal otherwise — resolved
-  /// from persistence so a headless bind (no `EstadoEcualizador`) still
-  /// reports honest gains.
-  Future<PresetEcualizador> _presetPersonalizadoAuto() async {
-    final servicio = ServicioEcualizador();
-    final config = await servicio.cargar();
-    final destino =
-        config.eqMultiDeviceEnabled
-            ? dispositivoDestinoEq(
-                multiDeviceEnabled: true,
-                dispositivo: await _dispositivoActivoAuto(),
-              )
-            : null;
-    return presetPersonalizadoEfectivo(config: config, deviceId: destino);
-  }
-
-  /// Per-parent children-changed subjects (feature auto-custom-eq):
-  /// audio_service subscribes to [subscribeToChildren]'s stream the first
-  /// time the platform loads a parent's children and translates every later
-  /// emission into a native `notifyChildrenChanged`, making the car
-  /// re-request `getChildren` so band titles and the selection mark refresh
-  /// right after a gain tap.
-  final Map<String, BehaviorSubject<Map<String, dynamic>>> _hijosSubjects = {};
-
-  @override
-  ValueStream<Map<String, dynamic>> subscribeToChildren(String parentMediaId) =>
-      _hijosSubjects.putIfAbsent(
-        parentMediaId,
-        () => BehaviorSubject.seeded(<String, dynamic>{}),
-      );
-
-  /// Emits a children-changed notification for [parentMediaId] — a no-op
-  /// until the platform has browsed that parent at least once.
-  void _notificarHijosCambiados(String parentMediaId) {
-    _hijosSubjects[parentMediaId]?.add(<String, dynamic>{});
-  }
-
   @override
   Future<List<MediaItem>> getChildren(
     String parentMediaId, [
@@ -1032,23 +941,6 @@ class PluriWaveAudioHandler extends BaseAudioHandler
             fuenteLocal != null && await fuenteLocal.hayCarpetaConfigurada();
         return constructor.raiz(incluirMusicaLocal: incluirMusicaLocal);
       }
-      if (parentMediaId == ConstructorArbolAuto.idEcualizador) {
-        return [
-          ...constructor.presetsEq(PresetEcualizador.presets),
-          constructor.itemEqPersonalizado(),
-        ];
-      }
-      if (parentMediaId == ConstructorArbolAuto.idEqPersonalizado) {
-        return constructor.bandasEq(await _presetPersonalizadoAuto());
-      }
-      if (esBandaEqMediaId(parentMediaId)) {
-        final indice = indiceBandaEqDesde(parentMediaId);
-        if (indice == null) return const [];
-        return constructor.gananciasBandaEq(
-          indice,
-          await _presetPersonalizadoAuto(),
-        );
-      }
       final musicaLocal = await hijosMusicaLocal(
         parentMediaId,
         fuente: fuenteLocal,
@@ -1097,65 +989,10 @@ class PluriWaveAudioHandler extends BaseAudioHandler
     Map<String, dynamic>? extras,
   ]) async {
     try {
-      // EQ preset selection (Design ADR-3, Spec "EQ Preset Selection Applies
-      // Without Disturbing Playback"): FIRST branch, unconditional `return`,
-      // so an `eq_preset:` id can never fall through to the playback routing
-      // below. `aplicarPresetPorMediaId`'s seams are EQ-only (persist +
-      // apply) — there is no playback parameter to inject here.
-      if (esPresetMediaId(mediaId)) {
-        final servicio = ServicioEcualizador();
-        // Persistence targeting (feature auto-custom-eq): with multi-device
-        // EQ on and a non-builtin output device active, the tap persists a
-        // DEVICE-level entry so the selection sticks for the car's device
-        // instead of being shadowed by the hierarchy; otherwise (or on any
-        // headless query failure) it persists the global principal as
-        // before.
-        await aplicarPresetPorMediaId(
-          mediaId,
-          presets: PresetEcualizador.presets,
-          uuidActual: emisoraActual?.uuid,
-          clavesPorEmisora: () async =>
-              (await servicio.cargar()).porEmisora.keys.toSet(),
-          clavesMatriz: () async =>
-              (await servicio.cargar()).presetsMatriz.keys.toSet(),
-          dispositivoDestino: () => _dispositivoDestinoEqAuto(servicio),
-          persistirDispositivo: servicio.guardarPresetDispositivo,
-          persistirPrincipal: servicio.guardarPrincipal,
-          aplicar: aplicarPreset,
-        );
-        return;
-      }
-      // Custom-EQ gain selection (feature auto-custom-eq): same
-      // unconditional-return shape as the eq_preset branch above — an
-      // `eq_gain:` id can never fall through to playback routing.
-      if (esGananciaEqMediaId(mediaId)) {
-        final servicio = ServicioEcualizador();
-        await aplicarGananciaPorMediaId(
-          mediaId,
-          cargarConfig: servicio.cargar,
-          dispositivoDestino: () => _dispositivoDestinoEqAuto(servicio),
-          persistirDispositivo: servicio.guardarPresetDispositivo,
-          persistirPrincipal: servicio.guardarPrincipal,
-          aplicarBanda: setBanda,
-          uuidActual: emisoraActual?.uuid,
-          clavesPorEmisora: () async =>
-              (await servicio.cargar()).porEmisora.keys.toSet(),
-          clavesMatriz: () async =>
-              (await servicio.cargar()).presetsMatriz.keys.toSet(),
-        );
-        // Refresh the affected browse nodes so the band title under
-        // `Personalizado` and the `● ` selection mark reflect the new gain.
-        final ganancia = gananciaEqDesde(mediaId);
-        if (ganancia != null) {
-          _notificarHijosCambiados(ConstructorArbolAuto.idEqPersonalizado);
-          _notificarHijosCambiados(idBandaEq(ganancia.$1));
-        }
-        return;
-      }
       // Local-track playback (Design "Local Track Playback Reuses Existing
-      // Pipeline", Spec "User selects a local track"): SECOND branch,
-      // unconditional `return`, mirroring the eq_preset branch above — a
-      // `pista:` id never falls through to the station routing below.
+      // Pipeline", Spec "User selects a local track"): FIRST branch,
+      // unconditional `return` — a `pista:` id never falls through to the
+      // station routing below.
       if (esPistaMediaId(mediaId)) {
         final fuenteLocal = _fuenteMusicaLocalGlobal;
         if (fuenteLocal == null) return;
@@ -1166,10 +1003,10 @@ class PluriWaveAudioHandler extends BaseAudioHandler
         );
         return;
       }
-      // Folder-play actions (Design ADR-5, Phase 3 task 4.3): THIRD
-      // branch, after eq_preset/pista, before the station fallthrough —
-      // mirrors both branches above's unconditional-return shape so
-      // neither new action id can fall through to station routing.
+      // Folder-play actions (Design ADR-5, Phase 3 task 4.3): SECOND
+      // branch, after `pista:`, before the station fallthrough — mirrors the
+      // branch above's unconditional-return shape so neither new action id
+      // can fall through to station routing.
       final constructorArbol = ConstructorArbolAuto();
       final esAccionCarpeta =
           constructorArbol.esCarpetaLocalReproducirMediaId(mediaId) ||