RP-07 - Catalog Retirement-Evidence FK

Status: RESOLVED_BLOCKING

Normative deferred constraint:

ALTER TABLE qt001_cp.code_catalog_item
  ADD CONSTRAINT fk_code_catalog_item__retired_evidence
  FOREIGN KEY(retired_reason_evidence_id) REFERENCES qt001_cp.evidence_registry(evidence_id)
  ON UPDATE RESTRICT ON DELETE RESTRICT NOT DEFERRABLE;

The existing structural CHECK remains: active item means NULL retirement evidence; retired item means non-NULL evidence. The FK guarantees the evidence exists. It is included in the consolidated deferred order and sealed expected-constraint set. Fake evidence UUID rejects at PG FK level.