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>

internal/adapters/transcribe/timeout.go

@@ -0,0 +1,33 @@
+package transcribe
+
+import (
+	"context"
+	"time"
+
+	"git.d-ma.be/mathias/tapir/internal/domain"
+)
+
+// WithTimeout gives every call to b its own deadline. A wedged engine does not answer at
+// all (iguana after a Metal OOM, infra#273), and with only the job's deadline it used up
+// the whole job before a fallback could run -- and Chain then refuses the fallback because
+// the job context has expired. With its own deadline the call fails while the job is still
+// alive, which is exactly when the fallback, or the other engine, can take over.
+//
+// A zero or negative d returns b unchanged. The wrapper is invisible: Name is b's.
+func WithTimeout(b Backend, d time.Duration) Backend {
+	if d <= 0 {
+		return b
+	}
+	return timeoutBackend{Backend: b, d: d}
+}
+
+type timeoutBackend struct {
+	Backend
+	d time.Duration
+}
+
+func (t timeoutBackend) Transcribe(ctx context.Context, wavPath string) (domain.Transcription, error) {
+	ctx, cancel := context.WithTimeout(ctx, t.d)
+	defer cancel()
+	return t.Backend.Transcribe(ctx, wavPath)
+}