feat(permissions): add SMS permission screen and settings button; route from splash on Android

lib/screens/settings_screen.dart

@@ -12,6 +12,8 @@ import '../widgets/native_ad_widget.dart';
 import '../widgets/common/snackbar/app_snackbar.dart';
 import '../l10n/app_localizations.dart';
 import '../providers/locale_provider.dart';
+import 'package:permission_handler/permission_handler.dart' as permission;
+import '../services/sms_service.dart';
 
 class SettingsScreen extends StatelessWidget {
   const SettingsScreen({super.key});
@@ -476,6 +478,60 @@ class SettingsScreen extends StatelessWidget {
                 ),
               ),
 
+              // SMS 권한 설정
+              if (!kIsWeb && Platform.isAndroid)
+                GlassmorphismCard(
+                  margin:
+                      const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+                  padding: const EdgeInsets.all(8),
+                  child: FutureBuilder<bool>(
+                    future: SMSService.hasSMSPermission(),
+                    builder: (context, snapshot) {
+                      final hasPermission = snapshot.data ?? false;
+                      return ListTile(
+                        leading: const Icon(
+                          Icons.sms,
+                          color: AppColors.textSecondary,
+                        ),
+                        title: const Text(
+                          'SMS 권한',
+                          style: TextStyle(color: AppColors.textPrimary),
+                        ),
+                        subtitle: Text(
+                          AppLocalizations.of(context).smsPermissionRequired,
+                          style:
+                              const TextStyle(color: AppColors.textSecondary),
+                        ),
+                        trailing: hasPermission
+                            ? const Padding(
+                                padding: EdgeInsets.symmetric(horizontal: 8.0),
+                                child: Icon(Icons.check_circle,
+                                    color: Colors.green),
+                              )
+                            : ElevatedButton(
+                                onPressed: () async {
+                                  final granted =
+                                      await SMSService.requestSMSPermission();
+                                  if (!granted) {
+                                    final status =
+                                        await permission.Permission.sms.status;
+                                    if (status.isPermanentlyDenied) {
+                                      await permission.openAppSettings();
+                                    }
+                                  }
+                                  if (context.mounted) {
+                                    // 상태 갱신을 위해 다시 build 트리거
+                                    (context as Element).markNeedsBuild();
+                                  }
+                                },
+                                child: Text(AppLocalizations.of(context)
+                                    .requestPermission),
+                              ),
+                      );
+                    },
+                  ),
+                ),
+
               // 앱 정보
               GlassmorphismCard(
                 margin: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),