feat: add payment card grouping and analysis

lib/widgets/add_subscription/add_subscription_form.dart

@@ -10,6 +10,9 @@ import '../common/form_fields/date_picker_field.dart';
 import '../common/form_fields/currency_dropdown_field.dart';
 import '../common/form_fields/billing_cycle_selector.dart';
 import '../common/form_fields/category_selector.dart';
+import '../payment_card/payment_card_selector.dart';
+import '../payment_card/payment_card_form_sheet.dart';
+import '../../routes/app_routes.dart';
 // Glass 제거: Material 3 Card 사용
 // Material colors only
 
@@ -234,6 +237,35 @@ class AddSubscriptionForm extends StatelessWidget {
                     );
                   },
                 ),
+                const SizedBox(height: 20),
+                Text(
+                  AppLocalizations.of(context).paymentCard,
+                  style: const TextStyle(
+                    fontSize: 16,
+                    fontWeight: FontWeight.w600,
+                  ),
+                ),
+                const SizedBox(height: 8),
+                PaymentCardSelector(
+                  selectedCardId: controller.selectedPaymentCardId,
+                  onChanged: (cardId) {
+                    setState(() {
+                      controller.selectedPaymentCardId = cardId;
+                    });
+                  },
+                  onAddCard: () async {
+                    final newCardId = await PaymentCardFormSheet.show(context);
+                    if (newCardId != null) {
+                      setState(() {
+                        controller.selectedPaymentCardId = newCardId;
+                      });
+                    }
+                  },
+                  onManageCards: () {
+                    Navigator.of(context)
+                        .pushNamed(AppRoutes.paymentCardManagement);
+                  },
+                ),
               ],
             ),
           ),