Improve the frontend

frontend/src/components/layout/Header/Header.tsx

@@ -102,6 +102,16 @@ export const Header = forwardRef<HeaderRef, HeaderProps>(({
 
   const [isNotificationPanelOpen, setIsNotificationPanelOpen] = useState(false);
 
+  // Filter notifications to last 24 hours for the notification bell
+  // This prevents showing old/stale alerts in the notification panel
+  const recentNotifications = React.useMemo(() => {
+    const oneDayAgo = Date.now() - (24 * 60 * 60 * 1000);
+    return notifications.filter(n => {
+      const alertTime = new Date(n.timestamp).getTime();
+      return alertTime > oneDayAgo;
+    });
+  }, [notifications]);
+
   const defaultSearchPlaceholder = searchPlaceholder || t('common:forms.search_placeholder', 'Search...');
 
   // Expose ref methods
@@ -259,7 +269,7 @@ export const Header = forwardRef<HeaderRef, HeaderProps>(({
               </Button>
 
               <NotificationPanel
-                notifications={notifications}
+                notifications={recentNotifications}
                 isOpen={isNotificationPanelOpen}
                 onClose={() => setIsNotificationPanelOpen(false)}
                 onMarkAsRead={markAsRead}