fix(eq): resolve base-speaker preset live instead of pinning a stale copy

_onDispositivoCambiado() bootstrapped a device-level preset entry for
every never-seen device id, including the built-in speaker. That
persistent level-3 entry masked later global-preset edits (level 3
beats level 4 on every resolution), so disconnecting a BT device or
cold-starting without one could leave the EQ stuck on an outdated
copy instead of the current global preset.

The base speaker is now excluded from the first-seen bootstrap:
disconnect and cold start always resolve through the live hierarchy.
BT/wired/USB devices keep their bootstrap behavior unchanged.

lib/estado/estado_ecualizador.dart

@@ -212,8 +212,13 @@ class EstadoEcualizador extends ChangeNotifier {
 
     _dispositivoActualId = dispositivo.id;
 
-    // First-seen device: copy the current resolved preset as its starting point.
-    if (!_presetsDispositivo.containsKey(dispositivo.id)) {
+    // First-seen device: copy the current resolved preset as its starting
+    // point. builtin_speaker is excluded: it must always fall through to
+    // the hierarchy (L4 global) instead of being pinned by a forced L3
+    // device-level copy, otherwise a later global-preset change would be
+    // masked by this stale entry for the base device.
+    final esBase = dispositivo.tipo == TipoDispositivo.altavozInterno;
+    if (!esBase && !_presetsDispositivo.containsKey(dispositivo.id)) {
       final presetBase = _resolverPresetActivo();
       _presetsDispositivo[dispositivo.id] = presetBase;
       await servicio.guardarPresetDispositivo(dispositivo.id, presetBase);