Add production health checks

README.md

@@ -47,6 +47,23 @@ The default `docker-compose.yml` is development-only. It mounts source files, in
 
 ## Operations
 
+### Health checks
+
+Monitor these production checks:
+
+- Frontend: `GET https://your-host/healthz`
+  - Verifies Nginx is serving the frontend container.
+- Backend liveness: `GET https://your-host/api/health/live`
+  - Verifies the API process is running.
+- Backend readiness: `GET https://your-host/api/health/ready`
+  - Verifies the API can reach Postgres and Redis. Returns `503` if either dependency is unavailable.
+- Backend metrics: `GET https://your-host/api/metrics`
+  - Admin-authenticated process, request, and queue metrics.
+- Postgres and Redis:
+  - Use the Docker health checks in `docker-compose.prod.yml`.
+- Worker:
+  - Use the Docker health check in `docker-compose.prod.yml`; it validates worker dependencies. The worker does not expose HTTP.
+
 ### Backups
 
 Create a compressed Postgres backup from the Docker Compose Postgres service: