We weren't handling these really before, just rendering the URI. This
should provide best-effort support for what we can render.

<img width="800" height="359" alt="image"
src="https://github.com/user-attachments/assets/51f101c7-c3be-4801-9000-62000a71faa6"
/>

(I will remove the extra labels that was just for testing)

Release Notes:

- acp: Support embedded resources in tool calls.