minor fixes

lib/screens/gateway/gateway_web_screen.dart

@@ -1,6 +1,6 @@
 import 'package:flutter/material.dart';
-import 'package:flutter_dotenv/flutter_dotenv.dart';
 import 'package:go_router/go_router.dart';
+import 'package:qpay/config/app_config.dart';
 import 'package:qpay/models/responsive_policy.dart';
 import 'package:qpay/screens/gateway/gateway_controller.dart';
 import 'package:qpay/browser.dart';
@@ -34,9 +34,7 @@ class _GatewayWebScreenState extends State<GatewayWebScreen> {
       redirecting = true;
     });
 
-    bool simulate = bool.parse(
-      dotenv.env['SIMULATE_PAYMENT_SUCCESS'] ?? 'false',
-    );
+    bool simulate = AppConfig.simulatePaymentSuccess;
     if (simulate) {
       // In simulation mode, just go to polling
       WidgetsBinding.instance.addPostFrameCallback((_) {