Screening sources manifest: sanctions and PEP source lists, per-source staleness (max_age_hours), attribution, and covered regimes

Source configuration and coverage manifest for the entity-screening corpus: which sanctions and PEP source lists are loaded, each list's freshness and staleness threshold (max_age_hours), per-source attribution and provenance under its public reuse terms, the covered sanctions regimes (covered_regimes), and an explicit statement of what is not covered. Use it to inspect source configuration, list freshness, and whether a regime such as US OFAC SDN (ofac_sdn) is in scope before screening. A metadata endpoint: it reports loaded state (always 200), never a screening verdict.