fix: Audio queue for sequential TTS playback (no overlap/skip)

- Audio packets queued instead of stopping previous
- _playNext() plays sequentially, each sentence after the previous
- stopPlayback() clears queue
- Fixes overlapping/skipping with XTTS sentence-by-sentence rendering

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

android/src/services/audio.ts

@@ -55,6 +55,10 @@ class AudioService {
   private recorder: AudioRecorderPlayer;
   private recordingPath: string = '';
 
+  // Audio-Queue fuer sequentielle TTS-Wiedergabe
+  private audioQueue: string[] = [];
+  private isPlaying: boolean = false;
+
   // VAD State
   private vadEnabled: boolean = false;
   private lastSpeechTime: number = 0;
@@ -198,15 +202,27 @@ class AudioService {
 
   // --- Wiedergabe ---
 
-  /** Base64-kodiertes Audio abspielen (z.B. TTS-Antwort von ARIA) */
+  /** Base64-kodiertes Audio in die Queue stellen und abspielen */
   async playAudio(base64Data: string): Promise<void> {
     if (!base64Data) return;
 
-    // Laufende Wiedergabe stoppen
+    this.audioQueue.push(base64Data);
-    this.stopPlayback();
+    if (!this.isPlaying) {
+      this._playNext();
+    }
+  }
+
+  /** Naechstes Audio aus der Queue abspielen */
+  private async _playNext(): Promise<void> {
+    if (this.audioQueue.length === 0) {
+      this.isPlaying = false;
+      return;
+    }
+
+    this.isPlaying = true;
+    const base64Data = this.audioQueue.shift()!;
 
     try {
-      // Base64 -> temporaere WAV-Datei -> Sound abspielen
       const tmpPath = `${RNFS.CachesDirectoryPath}/aria_tts_${Date.now()}.wav`;
       await RNFS.writeFile(tmpPath, base64Data, 'base64');
 
@@ -214,6 +230,7 @@ class AudioService {
         if (error) {
           console.error('[Audio] Fehler beim Laden:', error);
           RNFS.unlink(tmpPath).catch(() => {});
+          this._playNext();
           return;
         }
         this.currentSound?.play((success) => {
@@ -225,15 +242,20 @@ class AudioService {
           this.currentSound?.release();
           this.currentSound = null;
           RNFS.unlink(tmpPath).catch(() => {});
+          // Naechstes Audio abspielen
+          this._playNext();
         });
       });
     } catch (err) {
       console.error('[Audio] Wiedergabefehler:', err);
+      this._playNext();
     }
   }
 
-  /** Laufende Wiedergabe stoppen */
+  /** Laufende Wiedergabe stoppen + Queue leeren */
   stopPlayback(): void {
+    this.audioQueue = [];
+    this.isPlaying = false;
     if (this.currentSound) {
       this.currentSound.stop();
       this.currentSound.release();