agent2: Port more Zed AI features (#36559)

Release Notes:

- N/A

---------

Co-authored-by: Danilo Leal <daniloleal09@gmail.com>

crates/ui/src/components/callout.rs

@@ -81,7 +81,8 @@ impl Callout {
         self
     }
 
-    /// Sets an optional tertiary call-to-action button.
+    /// Sets an optional dismiss button, which is usually an icon button with a close icon.
+    /// This button is always rendered as the last one to the far right.
     pub fn dismiss_action(mut self, action: impl IntoElement) -> Self {
         self.dismiss_action = Some(action.into_any_element());
         self