urn:aauth:vocabulary:openapi-gateway — resources fronting multiple
OpenAPI-described services behind one identifier (AAuth R3 §OpenAPI Gateway
Vocabulary). Discovery value is a service-label → spec-URL object; operations
are addressed as service:operationId composites; R3 entries carry
{service, operationId} via the new optional formatOperationEntry on the
adapter contract. r3_vocabularies / docUrl types widened to the union
(persisted string entries stay valid).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WQ6weToT5UQaSJwKmezt6S