fix(popups): Fix goroutine leak in both HUD and Notifications

This likely leaks callbacks too, and eventually crashes.

cmd/hyprpanel-client/hud.go

@@ -229,7 +229,10 @@ func (h *hud) update(data *eventv1.HudNotificationValue) error {
 	h.showNotification()
 
 	go func() {
-		<-h.timer.C
+		select {
+		case <-h.timer.C:
+		case <-h.itemClosed:
+		}
 		h.closeItem()
 	}()
 

cmd/hyprpanel-client/notification_item.go

@@ -312,7 +312,11 @@ func (i *notificationItem) build(container *gtk.Box) error {
 	})
 
 	go func() {
-		<-i.timer.C
+		select {
+		case <-i.timer.C:
+		case <-i.closed:
+		}
+
 		i.close()
 	}()