The door lock reports changes to the user list (add / modify / delete users), and the server synchronizes and updates the cloud user data, supporting various user types such as fingerprint, card, password, face, palm print, and remote control.Linkage logic: Corresponds to the interfaces for issuing the "add / modify / delete lock user" and "synchronize door lock user" commands, and reports when the device user list changes.Use case: The server maintains door lock user data to ensure consistency with the device-side user list, used for updating data on the user management page.