fix: EdgeTtsManager val 赋值编译错误

apply 块内 isPlaying 赋值改为外部引用，避免 val 重新赋值。

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/src/main/java/com/xiaoqu/watch/service/manager/EdgeTtsManager.kt

@@ -289,23 +289,23 @@ class EdgeTtsManager @Inject constructor(
         withContext(Dispatchers.Main) {
             try {
                 stop()
-                mediaPlayer = MediaPlayer().apply {
+                val player = MediaPlayer()
-                    setDataSource(file.absolutePath)
+                player.setDataSource(file.absolutePath)
-                    setOnCompletionListener {
+                player.setOnCompletionListener {
                     isPlaying = false
                     onComplete?.invoke()
                     Timber.d("$TAG: 播放完成")
                 }
-                    setOnErrorListener { _, what, extra ->
+                player.setOnErrorListener { _, what, extra ->
                     Timber.e("$TAG: 播放错误 what=$what extra=$extra")
                     isPlaying = false
                     true
                 }
-                    prepare()
+                player.prepare()
-                    start()
+                player.start()
+                mediaPlayer = player
                 isPlaying = true
                 Timber.d("$TAG: 开始播放")
-                }
             } catch (e: Exception) {
                 Timber.e(e, "$TAG: 播放异常")
                 isPlaying = false