Health Check (deep)

Deep liveness probe for the RESTFul API service. Checks that the serving instance can actually reach Postgres and Redis.

This endpoint breaks the usual conventions on purpose — it is infrastructure, not a REST resource:

• No authentication. It sits outside the auth:restful-api group because Cloud Run’s probe sends no credentials, and it is not domain-locked either.
• Returns a raw body {"status": "ok", "checks": {"database": true, "redis": true}} with HTTP 200, or the same shape with "status": "unhealthy" and HTTP 503 — not the 201 + envelope every other endpoint uses.

For an authenticated “are my credentials working” check, use GET /api/v1/ping instead.