feat: upload audio, get a private Swedish transcript, discuss it (#33, ADR-033) (#39)

Upload a recording (audio, or video with the camera off), get a private Swedish transcript, and chat about it.

- ADR-033: RLS-scoped private transcript store; ffprobe/ffmpeg intake; gateway transcription (iguana kb-whisper, berget fallback); in-process single-replica worker; chat over the transcript (local models only).
- ADR-034: optional two-engine mode (pianissimo + kb-whisper) reconciled by a LOCAL model; off unless TAPIR_RECONCILE_BASE_MODEL is set.
- ADR-035: real progress (phases, running/quiet/lost), phase logging, every judged spot stored, merged segments.
- Hardening from four adversarial reviews: errors logged and stored as kinds never text; per-engine deadlines; converted-length check; bounded queue; client hang-ups are not errors; strict local-alias check.
- Dockerfile: static ffmpeg/ffprobe 7.0.2 pinned by sha256 (#34). Built and inspected by hand; CI does not build the image on a PR, so its first CI build is this merge.

Uploads stay OFF until TAPIR_UPLOADS_ENABLED is set in the deployment.

Closes #33, #34, #42, #43, #44.

Co-authored-by: Mathias <mthbqv@gmail.com>

docs/homelab-integration.md

@@ -12,6 +12,28 @@ it** — endpoints and aliases drift, and this file is a snapshot (2026-06-06),
   - **Off-cluster (host / NodePort):** `http://koala:30401/v1/` — service `litellm-nodeport` (`4000:30401`).
   - NOTE: the earlier `31234` was **wrong** — `31234` is the `llama-swap` NodePort (`8080:31234`),
     not LiteLLM. Use `30401` for off-cluster LiteLLM. `confirm` resolved.
+- **Speech-to-text (ADR-033):** the same gateway serves `POST /v1/audio/transcriptions` for
+  `iguana/kb-whisper` (primary, local) and `berget/kb-whisper` (fallback, EU cloud — private audio
+  leaves the homelab if it is used). **Call it via the NodePort / in-cluster address above, NOT
+  `https://llm-api.d-ma.be`:** that public ingress (openresty) returns `413` for bodies over
+  roughly 8–10 MB (~5 minutes of 16 kHz WAV), while the NodePort took 174 MB (90 minutes) in one
+  request (measured 2026-10-01, `docs/research/audio-length-ceiling-2026-10-01.md`). Send multipart
+  field `file`, `response_format=verbose_json`, no `Expect: 100-continue`. iguana's whisper-server
+  can wedge permanently after a Metal OOM (infra#273); never branch on its
+  `{"error":"failed to process audio"}` string — it has had at least five causes. Tapir's knobs:
+  `TAPIR_UPLOADS_ENABLED` (off by default), `TAPIR_UPLOAD_MAX_MB` (200), `TAPIR_UPLOAD_MAX_MINUTES`
+  (90), `TAPIR_TRANSCRIBE_MODEL`, `TAPIR_TRANSCRIBE_FALLBACK_MODEL` (empty disables the cloud
+  fallback), `TAPIR_TRANSCRIBE_TIMEOUT` (60m, the whole job), `TAPIR_TRANSCRIBE_ENGINE_TIMEOUT` (20m, one engine call: a wedged engine then fails while the job lives and the fallback can run), `TAPIR_UPLOAD_TMP_DIR`, `TAPIR_FFMPEG_BIN`,
+  `TAPIR_FFPROBE_BIN`, `TAPIR_MAX_UPLOADED_TRANSCRIPT_CHARS` (90000 — the measured ceiling of
+  `iguana/gemma4-26b`, which silently drops the head above it), `TAPIR_UPLOAD_CHAT_MODEL`
+  (`iguana/gemma4-26b`; must be a local `koala/` or `iguana/` alias, since the whole private transcript is sent to it; `koala/phi4-mini`'s 8,192-token context 400s on an hour of speech). `ffmpeg` + `ffprobe` are in the runtime image (static, pinned by sha256; #34 decided A on 2026-10-02); Tapir's own ingress body limit for a 200 MB upload is unverified (infra).
+  **Two-engine mode (ADR-034), off unless `TAPIR_RECONCILE_BASE_MODEL` is set:** it runs
+  `iguana/pianissimo` (the base text) and `TAPIR_TRANSCRIBE_MODEL` (kb-whisper) on the same audio, then a
+  LOCAL chat model (`TAPIR_RECONCILE_MODEL`) chooses between their disagreements. **Deployment choice (2026-10-02): `iguana/gemma4-31b`** (97% against a speaker's blind answers; 92% for `iguana/gemma4-26b`). With iguana's macOS **Low Power Mode off** the 31B decodes at 22 tok/s and reconciled a 63.6-minute recording in 21 min 49 s end to end; with it on it ran at 8 tok/s. Check `pmset -g | grep lowpowermode` before blaming a model or an engine for slowness.
+  `TAPIR_RECONCILE_CHECK_ORDER=true` asks twice per dispute with the order swapped (doubles the time).
+  Every model must start `koala/` or `iguana/`: a cloud alias is a start-up error. The default job timeout is
+  60 minutes. `iguana/pianissimo` is KlangAI's Swedish ASR (a Parakeet/FastConformer on MLX, served by a small
+  FastAPI shell on iguana:8102) and speaks the same `/v1/audio/transcriptions` API.
 - **Auth key:** treat as a secret via the SecretStore port; do not hardcode in committed code.
   NOTE: the documented `sk-local-123` returned `401` on `30401/v1/models` (2026-06-02) — it is
   stale or the gateway now enforces the `LITELLM_MASTER_KEY` (1Password `op://HomeLab/LITELLM_MASTER_KEY`).