Permanently delete a verifier

Permanently and immediately erase a caller-owned scope=user verifier. The verifier, all its versions (criterion, calibration examples, input contracts), all run records, and all access grants are removed from the live system at once. There is no recovery path. Use DELETE /{verifier_id} (revoke) to deactivate without erasing, keeping the audit trail intact. Serving gate: if any live published template version carries a snapshot that references this verifier, deletion is refused (409). Unpublish the relevant template version(s) first, then retry. Platform scope=system verifiers and another user's verifiers always surface as 404. Encrypted backups age out within the platform's standard retention window (up to three months), so the data is not instantly erased from all systems everywhere, but it is no longer accessible through any product surface after this call. Returns {verifier_id, name, deleted: true}.