Notify when tool is finished (#27459)

Now if a tool call finishes (or is blocked on confirmation) and the Zed
window is not active, you get a notification popup. You can turn it off
with a setting.

<img width="420" alt="Screenshot 2025-03-25 at 5 19 25 PM"
src="https://github.com/user-attachments/assets/bdf7b6b8-4428-4b46-8b09-e0be140f8a51"
/>
<img width="420 alt="Screenshot 2025-03-25 at 5 18 13 PM"
src="https://github.com/user-attachments/assets/1325e7b8-cd5a-44b9-a82d-5db928ad3cfc"
/>

Release Notes:

- N/A

---------

Co-authored-by: Agus Zubiaga <hi@aguz.me>
Co-authored-by: Danilo Leal <daniloleal09@gmail.com>

crates/assistant2/src/thread.rs

@@ -352,6 +352,10 @@ impl Thread {
             .filter(|tool_use| tool_use.status.needs_confirmation())
     }
 
+    pub fn has_pending_tool_uses(&self) -> bool {
+        !self.tool_use.pending_tool_uses().is_empty()
+    }
+
     pub fn checkpoint_for_message(&self, id: MessageId) -> Option<ThreadCheckpoint> {
         self.checkpoints_by_message.get(&id).cloned()
     }
@@ -1161,6 +1165,7 @@ impl Thread {
                         messages.clone(),
                         tool,
                     );
+                    cx.emit(ThreadEvent::ToolConfirmationNeeded);
                 } else {
                     self.run_tool(
                         tool_use.id.clone(),
@@ -1539,6 +1544,7 @@ pub enum ThreadEvent {
         canceled: bool,
     },
     CheckpointChanged,
+    ToolConfirmationNeeded,
 }
 
 impl EventEmitter<ThreadEvent> for Thread {}