Detach bridged-call ownership from bot speech failures

After a warm transfer succeeds, failures in bot-only speech services must not control the human bridge lifecycle. A fatal STT, TTS, or LLM pipeline error may correctly stop the bot, but its transport departure must not be interpreted as the caller-human conversation ending. Split processing-pipeline ownership from room-control ownership, keep a minimal identity-aware observer, and permit destructive cleanup only from verified caller or receiving-human terminal signals. Otherwise an ancillary outage becomes a full call drop.

Applies when: a bot remains connected to or observes a LiveKit room after successful human handoff. Keywords: LiveKit Pipecat warm transfer STT fatal error bridge lifecycle cleanup