The backend image builds the web UI with scripts/build_frontend.sh and
serves it through docsgpt/ui.py, so the standalone Compose file drops the
frontend container. UI and API share port 7091, published on 127.0.0.1
unless DOCSGPT_BIND says otherwise. POSTGRES_PASSWORD is configurable, and
an optional https profile puts Caddy in front of a public domain.
docker-image-verify.yml starts the standalone stack on the image it built
and checks the API, the UI, /config.js and a client-side route on one port.