agent: Generate a notification when reaching tool use limit (#31894)

When reaching the consecutive tool call limit, the agent gets blocked
and without a notification, you wouldn't know that. This PR adds the
ability to be notified when that happens, and you can use either sound
_and_ toast, or just one of them.

Release Notes:

- agent: Added support for getting notified (via toast and/or sound)
when reaching the consecutive tool call limit.

crates/agent/src/agent_diff.rs

@@ -1372,6 +1372,7 @@ impl AgentDiff {
             | ThreadEvent::ToolFinished { .. }
             | ThreadEvent::CheckpointChanged
             | ThreadEvent::ToolConfirmationNeeded
+            | ThreadEvent::ToolUseLimitReached
             | ThreadEvent::CancelEditing => {}
         }
     }