refactor(player): 重构播放控制系统，移除 Howler.js 改用原生 HTMLAudioElement

- 新建 playbackController.ts，使用 generation-based 取消替代 playbackRequestManager 状态机
- audioService 重写：单一持久 HTMLAudioElement + Web Audio API，createMediaElementSource 只调一次
- playerCore 瘦身为纯状态管理，移除 handlePlayMusic/playAudio/checkPlaybackState
- playlist next/prev 简化，区分用户手动切歌和歌曲自然播完
- MusicHook 适配 HTMLAudioElement API（.currentTime/.duration/.paused）
- preloadService 从 Howl 实例缓存改为 URL 可用性验证
- 所有 view/component 调用者迁移到 playbackController.playTrack()

修复：快速切歌竞态、seek 到未缓冲位置失败、重启后自动播放循环提示、EQ 重建崩溃

src/renderer/store/modules/player.ts

@@ -75,7 +75,8 @@ export const usePlayerStore = defineStore('player', () => {
     const playHistoryStore = usePlayHistoryStore();
     playHistoryStore.migrateFromLocalStorage();
 
-    await playerCore.initializePlayState();
+    const { initializePlayState: initPlayState } = await import('@/services/playbackController');
+    await initPlayState();
     await playlist.initializePlaylist();
   };
 
@@ -112,11 +113,7 @@ export const usePlayerStore = defineStore('player', () => {
     getVolume: playerCore.getVolume,
     increaseVolume: playerCore.increaseVolume,
     decreaseVolume: playerCore.decreaseVolume,
-    handlePlayMusic: playerCore.handlePlayMusic,
-    playAudio: playerCore.playAudio,
     handlePause: playerCore.handlePause,
-    checkPlaybackState: playerCore.checkPlaybackState,
-    reparseCurrentSong: playerCore.reparseCurrentSong,
 
     // ========== 播放列表管理 (Playlist) ==========
     playList,