docs: add audio TTS/STT research and GPU optimization documentation

- Add docs/audio/tts-research.md with Voxtral TTS, Kokoro-FastAPI, openedai-speech comparison
- Add docs/audio/stt-research.md with Voxtral STT, faster-whisper options
- Add docs/gpu/optimization.md with OLLAMA_KEEP_ALIVE and VRAM management
- Add docs/README.md with architecture overview
- Add index files for docs navigation

Research conducted April 2026 for future audio improvements

docs/gpu/README.md

@@ -0,0 +1,23 @@
+# GPU Documentation
+
+## Fichiers
+- [Optimization](optimization.md) - Optimisation VRAM et Ollama
+
+## Résumé
+
+### RX 7800 XT 16GB - Configuration
+| Paramètre | Valeur |
+|-----------|--------|
+| VRAM Totale | 16GB |
+| OLLAMA_KEEP_ALIVE | 0 |
+| qwen3.5:latest (Q4_K_M) | ~2.5GB |
+
+### Optimisations Appliquées
+- [x] OLLAMA_KEEP_ALIVE=0
+- [x] Service Ollama redémarré
+- [x] WoL Proxy timeout réduit
+- [ ] Monitoring Beszel+Dozzle
+
+---
+
+*Dernière mise à jour: Avril 2026*