Previously, NEXT_PUBLIC_API_URL was a build-time Next.js variable, making
it impossible to configure the backend URL in docker-compose `environment`
without rebuilding the image.
This change introduces a proper server-side proxy:
- next.config.ts: adds a rewrite rule that forwards all /api/* requests
to BACKEND_URL (read at server startup, not baked at build time).
Defaults to http://localhost:8000 so local dev works without config.
- api.ts: API_BASE is now an empty string — all fetch calls use relative
/api/... paths, which the Next.js server proxies to the backend.
- docker-compose.yml: replaces NEXT_PUBLIC_API_URL build arg with a
runtime BACKEND_URL env var defaulting to http://backend:8000, using
Docker's internal networking. Port 8000 no longer needs to be exposed.
- README: updates Docker setup docs, standalone compose example, and
environment variable reference to reflect BACKEND_URL.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Former-commit-id: b4c9e78cdd
David Parry