Display what the tool is doing (#27120)

<img width="639" alt="Screenshot 2025-03-19 at 4 56 47 PM"
src="https://github.com/user-attachments/assets/b997f04d-4aff-4070-87b1-ffdb61019bd1"
/>

Release Notes:

- N/A

---------

Co-authored-by: Agus Zubiaga <hi@aguz.me>

crates/assistant2/src/assistant_panel.rs

@@ -458,7 +458,7 @@ impl AssistantPanel {
 
             workspace.update_in(cx, |workspace, window, cx| {
                 let thread = thread.read(cx);
-                let markdown = thread.to_markdown()?;
+                let markdown = thread.to_markdown(cx)?;
                 let thread_summary = thread
                     .summary()
                     .map(|summary| summary.to_string())