v0.12.16

The community batch — **7 PRs from 5 external contributors**, plus the Teams live-transcript fixes and reliability work. Baseline v0.12.15.

## Highlights

**Google Meet & bots**
- **Leave-when-alone** — a bot alone in a meeting now emits `left_alone` and leaves instead of burning capacity for up to 4h (#545, @m-tauqueer). *Witnessed live on a real Google Meet.*
- **Lite bot no longer echoes** meeting audio back into the call (#819, @Ahmed-Tokyo). *Witnessed live.*
- **Redis first-use connect race** ("Socket already opened") fixed via idempotent memoized connect (#820, @Ahmed-Tokyo).

**Teams / mixed lane**
- **Live transcripts render in real time** — the mixed-lane mapper now stamps `absolute_start_time`, so Teams/Zoom transcripts paint live on the dashboard instead of only after a reload (#895).
- **Stable speaker labels** — unattributed turns show a single "Speaker" instead of a new fake speaker per line (#890).

**Transcription**
- **Bring-your-own STT** — any OpenAI-compatible endpoint, documented (#537, @LauraGPT).
- **Degraded STT reports *why*** on the terminal lifecycle event instead of completing silently (#552).
- Google Meet **silence-hallucination** suppression (ja/tr phrase lists + near-silent submit gate).

**API & correctness**
- Malformed `native_meeting_id` → **typed 422 at intake**, not an asyncpg 500 (#843).
- Meeting **timestamps serialize as UTC (`Z`)** so clients render local time correctly (#860, @jacobschooley).
- Zoom URLs now accepted in the join dialog (#897); honest version surfacing on webapp + dashboard (#72).

## Honest boundaries
- `left_alone` does not yet fire on Zoom/Teams/Jitsi when the bot is alone *from the start* (readiness latches on first audio) — #866.
- Community-contributed STT examples (FunASR/SenseVoice) are marked unwitnessed — #863.
- Dashboard browser logout has a known gap — #899. Mixed-lane transcript *quality* (oversplit/hallucination) is the focus of v0.12.17 (#847).

**Contributors:** Mohammad Tauqueer, LauraGPT, Ahmed Tokyo, Jacob Schooley, Dmitriy Grankin.

Full changelog: https://docs.vexa.ai/changelog · Integration PR: #867