Fix ROOT_PATH-aware health check and improve local deployment docs

[rbardaji]

Closes #185

Summary

Onboarding a new deployer surfaced one real bug and several documentation gaps that made a working installation look broken. This PR fixes all of them.

The health check bug (most impactful)

The container health check was hardcoded to http://localhost/health, which goes through nginx. When ROOT_PATH is set (e.g. /ep-api), nginx serves the API under ${ROOT_PATH}/, so http://localhost/health returns 404 and the container is reported unhealthy indefinitely even though the API is fully functional.

Verified on a live container running with ROOT_PATH=/ep-api:

• localhost/health (via nginx, what the check used) → 404
• localhost:8000/health (uvicorn directly) → 200

Both health checks now probe uvicorn directly at http://localhost:8000/health, which is independent of nginx and ROOT_PATH and correctly reflects API liveness:

• docker-compose.yml
• Dockerfile.allinone

Documentation fixes

• example.env: replace the broken METRICS_ENDPOINT placeholder (NDP_FEDERATION_METRICS_ENDPOINT default to federation/test) with the real default collector URL, so copying the file verbatim yields a valid config.
• example.env: clarify that CKAN_URL / CKAN_API_KEY stay empty on the MongoDB backend, and that CKAN_LOCAL_ENABLED is the master "allow local catalog writes" switch for any backend — not a "use CKAN" flag.
• README.md: recommend starting only the profiles you need, and warn that the pelican / full profiles start the Pelican federation services, which need extra TLS/federation setup and will restart-loop on a fresh local machine. Added a "recommended local stack" example that excludes Pelican.

Version

Bumped to 0.32.1 (swagger_settings.py + CHANGELOG.md).

Testing

• Confirmed on the live container (with ROOT_PATH=/ep-api) that the new health-check command curl -f http://localhost:8000/health returns HTTP 200 / exit 0, while the old http://localhost/health returned 404.
• Changes are documentation + container configuration only; no API code paths change beyond the version string (existing tests mock the version, so none are affected).