feat(alarm): add alarm snapshot viewing functionality

frontend/src/pages/Dashboard.tsx

@@ -24,6 +24,10 @@ const Dashboard: React.FC = () => {
   const [recentAlerts, setRecentAlerts] = useState<Alert[]>([]);
   const [cameraStatus, setCameraStatus] = useState<any[]>([]);
 
+  const handleViewSnapshot = (alert: Alert) => {
+    window.open(`/api/alarms/${alert.id}/snapshot`, '_blank');
+  };
+
   useEffect(() => {
     fetchStats();
     fetchAlerts();
@@ -139,7 +143,7 @@ const Dashboard: React.FC = () => {
                     description={formatTime(alert.created_at)}
                   />
                   {alert.snapshot_path && (
-                    <Button type="link" size="small">
+                    <Button type="link" size="small" onClick={() => handleViewSnapshot(alert)}>
                       查看截图
                     </Button>
                   )}