Voice narration for AI GM

[jeffbulltech]

• Integrate a text-to-speech engine (e.g., browser Web Speech API, or a hosted service like ElevenLabs/Coqui) to read AI GM responses aloud
• Add playback controls (play/pause/stop, speed, voice selection) alongside chat messages
• Support per-user or per-campaign voice/style preferences
• Stream narration incrementally as the AI GM response is generated rather than waiting for the full message to complete
• Provide a toggle to enable/disable voice narration, with graceful fallback to text-only when TTS is unavailable or fails
• Cache generated audio for frequently repeated content (e.g., campaign welcome messages) to reduce latency and API cost