fix(ui): use runtime ROOT_PATH for API base URL (#95)

[rbardaji]

Summary

Fixes #95 — The React UI was not using ROOT_PATH when making API calls, causing 404 errors behind a reverse proxy with a path prefix (e.g., /ep-api).

Changes

• entrypoint.sh (new): Generates /app/ui/build/config.js at container startup with the ROOT_PATH value from the environment
• ui/public/index.html: Loads config.js before the React app starts
• ui/src/services/api.js: Reads base URL from window.__EP_CONFIG__.rootPath instead of build-time REACT_APP_API_BASE_URL
• Dockerfile.allinone: Uses entrypoint.sh instead of launching supervisord directly

How it works

1. Container starts → entrypoint.sh runs
2. Script writes window.__EP_CONFIG__ = { rootPath: "/ep-api" }; to /app/ui/build/config.js
3. index.html loads this script before React boots
4. api.js picks up the rootPath as the axios base URL
5. Supervisord launches nginx + uvicorn as before

To change the prefix, just update ROOT_PATH in .env and restart — no rebuild needed.

Test plan

• All 1011 tests pass
• Container starts correctly with entrypoint.sh
• config.js is generated with correct ROOT_PATH value