fix(player): 静音保留原音量，解除后可恢复

- playerCore 新增持久化 isMuted 状态及 setMuted/toggleMute，静音时音频输出置 0 但 volume 保持不变
- 音量 > 0 时自动解除静音
- useVolumeControl 移除原 0↔30 切换；滑块/百分比展示真实音量，图标反映静音态
- 三个播放栏的音量滑块在静音时 disabled；PlayBar 百分比文字同步置灰（仅文字颜色）

src/renderer/store/modules/player.ts

@@ -41,6 +41,7 @@ export const usePlayerStore = defineStore('player', () => {
     musicFull,
     playbackRate,
     volume,
+    isMuted,
     userPlayIntent,
     isFmPlaying
   } = storeToRefs(playerCore);
@@ -97,6 +98,7 @@ export const usePlayerStore = defineStore('player', () => {
     musicFull,
     playbackRate,
     volume,
+    isMuted,
     userPlayIntent,
     isFmPlaying,
 
@@ -113,6 +115,8 @@ export const usePlayerStore = defineStore('player', () => {
     getVolume: playerCore.getVolume,
     increaseVolume: playerCore.increaseVolume,
     decreaseVolume: playerCore.decreaseVolume,
+    setMuted: playerCore.setMuted,
+    toggleMute: playerCore.toggleMute,
     handlePause: playerCore.handlePause,
 
     // ========== 播放列表管理 (Playlist) ==========