Document typed responses (202 SubmitAccepted / 400 / 401 on self-service; 200
OpenbaarEntry[] on openbaar) so the generated spec carries real schemas for S-08's
client. A document transformer clears the auto-populated servers block so the spec
is host-independent and deterministic. Commit services/bff/openapi.json and add a
test asserting it matches the served /openapi/v1.json (fails on drift).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
