fix: correct _inject_user signature to avoid circular import

dashboard/backend/rbac.py

@@ -138,13 +138,11 @@ def require_write():
     return checker
 
 
-async def _inject_user(request: Request, user = Depends(lambda: None)):
+async def _inject_user(request: Request):
     """Dependency to store user in request.state for rbac dependencies.
 
-    Note: This expects auth to be handled by a parent dependency.
     Import auth module at runtime to avoid circular imports.
     """
-    if user is None:
     import auth as auth_module
     user = await auth_module.get_current_user(request)
     request.state.user = user