List retained occurrences

Lists the retained occurrences of one schedule from its authoritative Scheduler Partition, ordered by durable creation instant and occurrence identifier so tied timestamps never duplicate or omit a row — oldest first unless order=newest, which walks from the most recent. A run that an edit replaced before it ran is left out; a run skipped because the previous one was still going is listed. The cursor is opaque, scoped to the verified principal's organization, project and environment, and to the order it was issued under. Each item is metadata only: callback payloads, destinations, response bodies and signing material have no field in the response.