Cut web-next over to the standalone GraphQL service

[dahlia]

Problem

Development and deployment configuration still allow web-next to use the GraphQL endpoint served by the legacy Fresh process on port 8000. The legacy application cannot be retired while it remains an API dependency.

Tasks

• Make the standalone GraphQL service the authoritative API endpoint in local development, Docker Compose, CI, staging, and production.
• Update API_URL, reverse-proxy routes, ports, service dependencies, and health checks.
• Confirm that authentication cookies and forwarded request metadata behave correctly across the new service boundary.
• Verify uploads, well-known resources, WebFinger, NodeInfo, ActivityPub routes, and GraphQL requests.
• Exercise independent API and federation-worker startup and shutdown.
• Document cutover and rollback procedures.

Acceptance criteria

• web-next never requires the Fresh process to serve GraphQL.
• All environments use the standalone GraphQL service consistently.
• Signed-in browser flows, uploads, federation endpoints, and health checks pass against the new topology.
• Staging or an equivalent production-like environment has exercised the cutover and rollback procedures.

AI assistance: This issue was drafted and organized with Codex after a maintainer-led code audit.