Non-breaking refactor — pickGuildExportMeshFetchMixinMethods() eliminates duplicate mixin builds; buildExportMeshFetchRegistryDiagnosticsSnapshot() surfaces export mesh registry on platform RPC view; audit/digest RPC mixins import consolidated platform-export-mesh-fetch-mixin directly. Default gossip v1 unchanged; fleet v2 cutover still deferred. Verification: test:ci-phase902, pear run boot, pearcord.log scan.