Health Check

Liveness + dependency health.

Probes every dependency the API relies on (Postgres, Anthropic key, the JWKS endpoint) concurrently and reports each under deps. The top-level status is "ok" when all are healthy, else "degraded". This always returns HTTP 200 (process liveness) — a degraded dependency shouldn't trigger a container restart, since jobs simply queue until the dependency recovers. Stripe is intentionally excluded: it's an external, billing-only dependency. Results are cached ~15s in-process.