Use-case-level BDD (Reqnroll) driving the real BFF over HTTP with fake downstreams
and locally-minted tokens: a valid DigiD token is accepted and the bsn forwarded
to the domain; a tokenless submit is 401; the openbaar register is anonymous and
never exposes the bsn (ADR-0010). Real Keycloak validation is the verify-bff check.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
