feat: XTTS v2 integration, auto-update system, TTS engine abstraction

- XTTS v2: Docker setup for Gaming-PC (GPU), bridge via RVS relay
- XTTS: Voice cloning UI in Diagnostic (multi-file upload)
- XTTS: Engine selectable (Piper local vs XTTS remote) with fallback
- Auto-Update: RVS serves APK over WebSocket (no HTTP needed)
- Auto-Update: App checks version on start, prompts install
- Auto-Update: release.sh copies APK to RVS via scp
- Bridge: TTS engine abstraction (piper/xtts), config persistent
- Bridge: xtts_response handler, tts_request on-demand
- Diagnostic: TTS engine dropdown, XTTS voice panel, voice cloning
- App: Play button on ARIA messages, chat search, update service
- Wake word: Disabled LiveAudioStream (crash fix), Phase 1 placeholder
- Watchdog: Container restart after 8min stuck
- Chat backup: on-the-fly to /shared/config/chat_backup.jsonl

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

xtts/docker-compose.yml

@@ -0,0 +1,54 @@
+# ════════════════════════════════════════════════
+#  ARIA XTTS v2 — GPU TTS Server
+#  Laeuft auf dem Gaming-PC (RTX 3060)
+#  Verbindet sich zum RVS fuer TTS-Requests
+# ════════════════════════════════════════════════
+#
+#  Voraussetzungen:
+#    - Docker Desktop mit WSL2
+#    - NVIDIA Container Toolkit
+#    - .env mit RVS-Verbindungsdaten
+#
+#  Start: docker compose up -d
+#  Test:  curl http://localhost:8000/docs
+# ════════════════════════════════════════════════
+
+services:
+
+  # ─── XTTS v2 API Server (GPU) ─────────────────
+  xtts:
+    image: ghcr.io/daswer123/xtts-api-server:latest
+    container_name: aria-xtts
+    deploy:
+      resources:
+        reservations:
+          devices:
+            - driver: nvidia
+              count: 1
+              capabilities: [gpu]
+    ports:
+      - "8000:8000"
+    volumes:
+      - xtts-models:/root/.local/share/tts     # Model-Cache (~2GB)
+      - ./voices:/voices                        # Custom Voice Samples
+    environment:
+      - COQUI_TOS_AGREED=1
+    restart: unless-stopped
+
+  # ─── XTTS Bridge (verbindet zu RVS) ───────────
+  xtts-bridge:
+    build: .
+    container_name: aria-xtts-bridge
+    depends_on:
+      - xtts
+    environment:
+      - XTTS_API_URL=http://xtts:8000
+      - RVS_HOST=${RVS_HOST}
+      - RVS_PORT=${RVS_PORT:-443}
+      - RVS_TLS=${RVS_TLS:-true}
+      - RVS_TLS_FALLBACK=${RVS_TLS_FALLBACK:-true}
+      - RVS_TOKEN=${RVS_TOKEN}
+    restart: unless-stopped
+
+volumes:
+  xtts-models: