text: Title: Unify frontend and backend language preference using shared cookie
  Body: ## Bug Report
  
  **Problematic behavior**
  Here you can see "Doc private" appears in English but the user interface is in French. 
  https://github.com/user-attachments/assets/0ae0e457-15f7-423c-b4bc-c1c5fc9d48bc
  
  Same when I'm loading a doc I don't have access to. The message only is available in French even if I sent the interface in English and reload.
  ![Capture d’écran du 2024-10-14 17-26-11](https://github.com/user-attachments/assets/0646afd7-f25a-4e9d-b7fe-2b7a6457db33)
  
  
  