Improve AI agents setting

When working on the content signals I saw in an example that they display AI agent options. I thought this was a nice and clear way to display the options. We could replace the `Allow AI Bots` setting with an `AI Agents Policy` and display these options:

<img width="623" height="705" alt="Image" src="https://github.com/user-attachments/assets/86cc8762-b8dc-4ff2-a270-195097bc4d28" />