Recovers 7 model classes (UserStorageQuota, AutomatedTask, ExternalKBService,
KnowledgeDocumentChunk, MCPServer, OSSStorageConfig, TaskExecutionLog) and the
gen_uuid helper that were lost in the mass file-deletion (5d7f32d). These are
required by the restored admin modules (storage_admin/asset_admin/etc). Verified
at runtime: /health=200 and all restored admin routers serve 200.
