Meridian: Multiple defense-in-depth gaps (collection/depth caps, telemetry, retry, fan-out)

Summary Meridian v2.1.0 Meridian.Mapping and Meridian.Mediator shipped with nine defense-in-depth gaps reachable through its public APIs. Two are HIGH severity — the advertised DefaultMaxCollectionItems and DefaultMaxDepth safety caps are silently bypassed on the IMapper.Mapsource, destination...