fix(model/user.py): Removed unnecesary methods

model/user.py

@@ -9,13 +9,4 @@ class User:
     password_hash: str
     name: str
     role: str
-    created_at: datetime
-
-    def is_admin(self) -> bool:
-        return self.role == 'admin'
-
-    def is_operator(self) -> bool:
-        return self.role == 'operator'
-
-    def is_viewer(self) -> bool:
-        return self.role == 'viewer'
+    created_at: datetime