completed first web iteration

lib/screens/gateway/gateway_controller.dart

@@ -76,15 +76,22 @@ class GatewayController extends ChangeNotifier {
   }
 
   Future<void> pollTransaction(String uid) async {
+    // only poll for 5 minutes
+    int max = 30;
     while (!model.isCancelled) {
+      max++;
       // Check cancellation flag instead of true
       // Wait 5 seconds before the next poll
-      await Future.delayed(const Duration(seconds: 5));
+      await Future.delayed(const Duration(seconds: 10));
 
       // Check again after delay in case it was cancelled during the delay
       if (model.isCancelled) break;
 
       await poll(uid);
+
+      if(max > 30) {
+        model.isCancelled = true;
+      }
     }
   }