fix(audio): publish idle from stop() instead of trusting the player

just_audio's playerStateStream is .distinct() over a value-equal
PlayerState, so stopping an already-idle player emits nothing. Paired
with the source-change mask -- which writes loading into playbackState
rather than filtering at read time -- a stop landing before native init
completed would leave the state at loading forever.

audio_service only tears the foreground service down on a non-idle to
idle transition, so that window produced an unkillable notification
stuck on "cargando" with a dead Stop button: strictly worse than the
teardown this branch removes.

Additive and idempotent -- when the player does emit its own idle, this
just lands first.

lib/servicios/servicio_audio.dart

@@ -1253,6 +1253,26 @@ class PluriWaveAudioHandler extends BaseAudioHandler
     _cambiandoFuente = false;
     _revisionFuente++;
     await _player.stop();
+    // Publish `idle` OURSELVES rather than trusting the player to emit it.
+    // `just_audio`'s `playerStateStream` is `.distinct()` over a value-equal
+    // `PlayerState`, so a stop landing on an already-idle player (a station
+    // change stopped before its native init finished pushing `loading`)
+    // emits NOTHING. Combined with the source-change mask above — which
+    // WRITES `loading` into `playbackState` rather than filtering at read
+    // time — that would leave the state stuck at `loading` forever:
+    // `audio_service` only tears the service down on a non-idle -> idle
+    // transition (`audio_service.dart:1131-1136`), so the notification would
+    // survive as an unkillable "cargando" with a dead Stop button. Strictly
+    // worse than the bug this branch fixes. Additive and idempotent: when
+    // the player DOES emit its own `idle`, this simply lands first and the
+    // duplicate is a no-op transition.
+    playbackState.add(
+      playbackState.value.copyWith(
+        processingState: AudioProcessingState.idle,
+        playing: false,
+        errorMessage: null,
+      ),
+    );
     emisoraActual = null;
     mediaItem.add(null);
     await super.stop();