thread view: Refine the UI a bit (#36504)

Release Notes:

- N/A

---------

Co-authored-by: Agus Zubiaga <agus@zed.dev>

crates/agent_ui/src/acp/entry_view_state.rs

@@ -189,6 +189,7 @@ pub enum ViewEvent {
     MessageEditorEvent(Entity<MessageEditor>, MessageEditorEvent),
 }
 
+#[derive(Debug)]
 pub enum Entry {
     UserMessage(Entity<MessageEditor>),
     Content(HashMap<EntityId, AnyEntity>),