Opt-in (lotusCallState=1) bridge that emits io.lotus.call_state with each
participant's speaking/audio/video state, so the Lotus host can drive
speaking rings / mute badges / PiP from real events instead of scraping
EC's rendered DOM. Exposes vm.userMedia$ on the public CallViewModel.
Additive: no-op without the flag.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
