Foundation for native LiveKit calling: the LiveKit iOS SDK carries the call media
natively and coordinates its audio engine with CallKit's AVAudioSession (AudioManager
.setEngineAvailability on didActivate/didDeactivate) — the thing WebKit's WebRTC can't
do. With this, the CallKit call stays active (stable ring + lock-screen answer +
background) AND the mic works. Native connection code + server LiveKit token in the VoIP
payload + WebView coordination come next. Don't build yet.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>