feat(user): add user type modification endpoint

- Implement new endpoint `/userMgr/modifyType` for updating user types
- Add database function DBUpdateUserType to handle type updates
- Include request validation and proper error handling
- Update API documentation with new endpoint details

router.go

@@ -21,7 +21,7 @@ func setupRoutes() {
 	http.HandleFunc("/userMgr/create", CreateUserHandler)
 	http.HandleFunc("/userMgr/remove", RemoveUserHandler)
 	http.HandleFunc("/userMgr/list", ListUserHandler)
-	// http.HandleFunc("/userMgr/modify", ModifyUserHandler)
+	http.HandleFunc("/userMgr/modifyType", ModifyUserTypeHandler)
 
 	http.HandleFunc("/sessionMgr/list", ListActiveSessionsHandler)
 	http.HandleFunc("/sessionMgr/remove", RemoveSessionHandler)