Release Connector Quarantine Endpoint

Staff-gated release for a quarantined pgstream Deployment.

Mirrors POST /v1/connectors/{cid}/quarantine/{qid}/release but lives under /internal/* so the connectors-health drilldown UI can release a quarantine without requiring its operator to also hold connectors.update on the customer's connector. Staff don't carry org membership for customer orgs; the per-connector check on the public endpoint would 403 them on every customer they're paged for.

Authorization: verify_staff_auth (is_ardent_staff = TRUE) only. Audit: released_by is set to the staff user_id, identical to the public endpoint, so the quarantine row's audit trail is preserved. Idempotent — already-released rows return the current state via mark_quarantine_released's fallback path.