通知中心全部控制逻辑已达成，即将进入后台与播放歌曲标题推送的优化

lib/audio/playback_state_manager.dart

@@ -17,23 +17,23 @@ class PlaybackStateManager {
   Duration get duration => _duration;
 
   // ⭐ 核心改动：使用 playPause 替代 play/pause 分离
+  // lib/audio/playback_state_manager.dart
   audio_service.PlaybackState get playbackState {
-    // ⭐ 固定使用 playPause，不再动态切换
     final playControl = audio_service.MediaControl(
       androidIcon: _playing ? 'drawable/ic_pause' : 'drawable/ic_play',
       label: _playing ? '暂停' : '播放',
-      action: audio_service.MediaAction.playPause, // 固定
+      action: audio_service.MediaAction.playPause,
     );
 
     final controls = [
       audio_service.MediaControl(
-        androidIcon: 'drawable/ic_previous',
+        androidIcon: 'drawable/ic_previous', // 上一首
         label: '上一曲',
         action: audio_service.MediaAction.skipToPrevious,
       ),
       playControl,
       audio_service.MediaControl(
-        androidIcon: 'drawable/ic_next',
+        androidIcon: 'drawable/ic_next', // 下一首
         label: '下一曲',
         action: audio_service.MediaAction.skipToNext,
       ),
@@ -42,10 +42,9 @@ class PlaybackStateManager {
     return audio_service.PlaybackState(
       controls: controls,
       processingState: audio_service.AudioProcessingState.ready,
-      playing: _playing, // ⭐ 这里才是真正的播放状态，通知栏会根据它显示正确的图标
-      androidCompactActionIndices: const [0, 1, 2],
+      playing: _playing,
+      androidCompactActionIndices: const [0, 1, 2], // 显示全部三个
       updateTime: DateTime.now(),
-      //extras: {'_refresh': DateTime.now().millisecondsSinceEpoch},
     );
   }