The "couple broadcast to voice" feature only wired auto-start into the
normal-bot join handler. Userbot mode (the only mode that can actually Go
Live) was added later with Go-Live deferred to a "stage 2" that never
landed, so the running deployment had no path to start a broadcast.
Extract the coupling into a shared bot/src/broadcast.ts (auto-start on
join, report live state to the brain each turn, voice toggle) and wire it
into both index.ts and userbot.ts so both modes behave identically. Add a
behavioural test for the auto-start + toggle contract.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>