feat: 알림 재예약 개선과 패키지 업그레이드

lib/screens/settings_screen.dart

@@ -1,5 +1,5 @@
 import 'package:flutter/material.dart';
-import 'package:flutter/foundation.dart' show kIsWeb;
+import 'package:flutter/foundation.dart' show kIsWeb, kDebugMode;
 import 'package:provider/provider.dart';
 import '../providers/notification_provider.dart';
 import 'dart:io';
@@ -694,6 +694,25 @@ class SettingsScreen extends StatelessWidget {
                                                     ),
                                                   ),
                                                 ),
+                                              if (kDebugMode)
+                                                Padding(
+                                                  padding:
+                                                      const EdgeInsets.only(
+                                                          top: 16.0),
+                                                  child: SizedBox(
+                                                    width: double.infinity,
+                                                    child: OutlinedButton.icon(
+                                                      icon: const Icon(Icons
+                                                          .notifications_active),
+                                                      label:
+                                                          const Text('테스트 알림'),
+                                                      onPressed: () {
+                                                        NotificationService
+                                                            .showTestPaymentNotification();
+                                                      },
+                                                    ),
+                                                  ),
+                                                ),
                                             ],
                                           ),
                                         ),