refactor: migrate Stripe checkout to external browser with lifecycle-based subscription refresh

lib/features/profile/presentation/widgets/billing_tab.dart

@@ -1,12 +1,10 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:flutter_svg/flutter_svg.dart';
-import 'package:go_router/go_router.dart';
 import 'package:intl/intl.dart';
 import 'package:url_launcher/url_launcher.dart';
 import 'package:real_estate_mobile/core/constants/app_colors.dart';
 import 'package:real_estate_mobile/features/profile/presentation/providers/profile_provider.dart';
-import 'package:real_estate_mobile/features/profile/presentation/screens/stripe_checkout_screen.dart';
 
 class BillingTab extends ConsumerStatefulWidget {
   const BillingTab({super.key});
@@ -15,16 +13,33 @@ class BillingTab extends ConsumerStatefulWidget {
   ConsumerState<BillingTab> createState() => _BillingTabState();
 }
 
-class _BillingTabState extends ConsumerState<BillingTab> {
+class _BillingTabState extends ConsumerState<BillingTab>
+    with WidgetsBindingObserver {
   Map<String, dynamic>? _subscription;
   bool _isLoadingSubscription = false;
+  bool _openedExternalCheckout = false;
 
   @override
   void initState() {
     super.initState();
+    WidgetsBinding.instance.addObserver(this);
     _loadSubscription();
   }
 
+  @override
+  void dispose() {
+    WidgetsBinding.instance.removeObserver(this);
+    super.dispose();
+  }
+
+  @override
+  void didChangeAppLifecycleState(AppLifecycleState state) {
+    if (state == AppLifecycleState.resumed && _openedExternalCheckout) {
+      _openedExternalCheckout = false;
+      _loadSubscription();
+    }
+  }
+
   Future<void> _loadSubscription() async {
     if (_isLoadingSubscription) return;
     setState(() => _isLoadingSubscription = true);
@@ -51,7 +66,10 @@ class _BillingTabState extends ConsumerState<BillingTab> {
         _subscription!['status'] == 'ACTIVE';
     final plan = _subscription?['plan'] as Map<String, dynamic>?;
 
-    return ListView(
+    return RefreshIndicator(
+      color: AppColors.accentOrange,
+      onRefresh: _loadSubscription,
+      child: ListView(
       padding: const EdgeInsets.fromLTRB(24, 10, 24, 30),
       children: [
         const Center(
@@ -109,6 +127,7 @@ class _BillingTabState extends ConsumerState<BillingTab> {
         const SizedBox(height: 24),
         _buildNeedHelpSection(),
       ],
+    ),
     );
   }
 
@@ -371,6 +390,15 @@ class _BillingTabState extends ConsumerState<BillingTab> {
                   ),
                 ],
               ),
+              const SizedBox(height: 12),
+              Text(
+                'By clicking this button you\'ll be taken to our website to complete your purchase.',
+                style: TextStyle(
+                  fontFamily: 'SourceSerif4',
+                  fontSize: 12,
+                  color: AppColors.primaryDark.withValues(alpha: 0.5),
+                ),
+              ),
               const SizedBox(height: 16),
               const Text(
                 'Include Features',
@@ -555,18 +583,13 @@ class _BillingTabState extends ConsumerState<BillingTab> {
       final repo = ref.read(profileRepositoryProvider);
       final url = await repo.createPortalSession();
       if (!mounted) return;
-      await Navigator.of(context, rootNavigator: true).push<Map<String, dynamic>?>(
-        MaterialPageRoute(
-          builder: (_) => StripeCheckoutScreen(
-            url: url,
-            title: 'Manage Subscription',
-          ),
-        ),
+      _openedExternalCheckout = true;
+      await launchUrl(
+        Uri.parse(url),
+        mode: LaunchMode.externalApplication,
       );
-      if (mounted) {
-        _loadSubscription();
-      }
     } catch (e) {
+      _openedExternalCheckout = false;
       if (mounted) _showSnackBar('Failed to open billing portal: $e', isError: true);
     }
   }
@@ -582,22 +605,13 @@ class _BillingTabState extends ConsumerState<BillingTab> {
       final planId = plans.first['id'] as String;
       final url = await repo.createCheckoutSession(planId);
       if (!mounted) return;
-      final result = await Navigator.of(context, rootNavigator: true).push<Map<String, dynamic>?>(
-        MaterialPageRoute(
-          builder: (_) => StripeCheckoutScreen(
-            url: url,
-            title: 'Checkout',
-            successUrlPattern: 'confirmation',
-          ),
-        ),
+      _openedExternalCheckout = true;
+      await launchUrl(
+        Uri.parse(url),
+        mode: LaunchMode.externalApplication,
       );
-      if (result != null && result['success'] == true && mounted) {
-        final sessionId = result['sessionId'] as String?;
-        context.go('/payment-success${sessionId != null ? '?session_id=$sessionId' : ''}');
-      } else if (mounted) {
-        _loadSubscription();
-      }
     } catch (e) {
+      _openedExternalCheckout = false;
       if (mounted) _showSnackBar('Failed to start checkout: $e', isError: true);
     }
   }