Add the use case diagram UCD-001, the user stories US-001 and the brief use cases UC-001 to UC-004 (Synchronize Repository Metadata, Configure Workflow Credentials, Onboard a Repository, Diagnose a Failed Workflow). Review and accept them (RC-019 to RC-024) and the PP-001 row that records them (RC-025), and update TM-001 and the registry. Task: MIL-002#1