Centralize CPU identity in models.ResolveCPUSerialNumber: an explicit source serial wins, otherwise a valid source PPIN is used, placeholders rejected. Dell, H3C and Redfish apply it while parsing; canonical-device and Reanimator conversion apply it again at the output boundary. No identity is synthesized from socket/model/board serial. See ADL-058. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>