List delivery attempts

Lists the immutable attempts retained under one occurrence, ordered by start instant and attempt identifier so equal timestamps have a stable position. The PostgreSQL authority answers every page. Optional first-outbound fields carry trusted occurrence timing and its pinned policy; absence means unknown, never zero. Results expose only bounded outcome, response-status, duration, timing, diagnostic, remediation and redelivery-cause metadata; callback payloads, response bodies, destinations, signing material, secrets and transport traces are structurally absent.