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/.env.example

@@ -0,0 +1,11 @@
+# ════════════════════════════════════════════════
+#  ARIA XTTS v2 — Konfiguration
+#  Kopieren nach .env und anpassen
+# ════════════════════════════════════════════════
+
+# RVS Verbindung (gleiche Daten wie auf der ARIA-VM)
+RVS_HOST=mobil.hacker-net.de
+RVS_PORT=444
+RVS_TLS=true
+RVS_TLS_FALLBACK=true
+RVS_TOKEN=dein_token_hier