Refactor code structure for improved readability and maintainability

app/schemas/user.py

@@ -1,6 +1,6 @@
 """User schemas."""
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
 
 
 class UserUpdate(BaseModel):
@@ -15,3 +15,13 @@ class UserUpdate(BaseModel):
     plan_id: int | None = Field(None, description="User plan ID")
     credits: int | None = Field(None, ge=0, description="User credits")
     is_active: bool | None = Field(None, description="Whether user is active")
+    role: str | None = Field(None, description="User role (admin or user)")
+
+    @field_validator("role")
+    @classmethod
+    def validate_role(cls, v: str | None) -> str | None:
+        """Validate that role is either 'user' or 'admin'."""
+        if v is not None and v not in {"user", "admin"}:
+            msg = "Role must be either 'user' or 'admin'"
+            raise ValueError(msg)
+        return v