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

lib/screens/splash_screen.dart

@@ -2,6 +2,8 @@ import 'dart:async';
 import 'dart:ui';
 import 'package:flutter/material.dart';
 import '../theme/app_colors.dart';
+import '../services/sms_service.dart';
+import '../utils/platform_helper.dart';
 import '../routes/app_routes.dart';
 import '../l10n/app_localizations.dart';
 
@@ -98,9 +100,20 @@ class _SplashScreenState extends State<SplashScreen>
     }
   }
 
-  void navigateToNextScreen() {
-    // 앱 잠금 기능 비활성화: 항상 MainScreen으로 이동
-    // 모든 이전 라우트를 제거하고 홈으로 이동
+  Future<void> navigateToNextScreen() async {
+    // Android에서 SMS 권한이 없으면 권한 안내 화면으로 이동
+    if (PlatformHelper.isAndroid) {
+      final hasPermission = await SMSService.hasSMSPermission();
+      if (!hasPermission && mounted) {
+        Navigator.of(context).pushNamedAndRemoveUntil(
+          AppRoutes.smsPermission,
+          (route) => false,
+        );
+        return;
+      }
+    }
+
+    if (!mounted) return;
     Navigator.of(context).pushNamedAndRemoveUntil(
       AppRoutes.main,
       (route) => false,