Chat screen now supports both:
- Text messaging (keyboard input)
- High-quality Ultravox voice calls (WebRTC)
Features:
- Voice call button in input bar (phone icon)
- Green status bar when call is active
- Transcripts from voice calls appear in chat history
- Voice badge on messages from voice conversation
- Mute button during calls
- Auto-end call when leaving screen
Background audio configured for iOS (audio, voip modes)
