Verify Registration

Deprecated — use verify_device_login (same behaviour).

Poll a device-authorization challenge to token issuance (UC-075, RFC 8628).

Anonymous. While the human has not yet acted, answers 202 {"status": "pending", "retry_after": <seconds>} — sleep that many seconds and call again with the same challenge_id. On approval, answers 200 with Keycloak's token set (access_token, refresh_token, expires_in, ...) handed over exactly once; every existing token-gated tool then works unchanged with that access_token.