AI assistant not responding, silently failing. Prob due to no credits

The AI assistant in the dashboard is not responding.

This may be caused by missing credits, but instead of silently failing the UI should show a clear error message so it is obvious what went wrong and what to do next.

<img width="338" height="755" alt="Image" src="https://github.com/user-attachments/assets/ace64b8d-92b1-4499-8c0f-c801e9f6334b" />