SAF初步修改，等待验证

lib/main.dart

@@ -1,7 +1,13 @@
 import 'package:flutter/material.dart';
 import 'pages/battery_health_page.dart';
+import 'services/saf_storage_service.dart';
+
+void main() async {
+  WidgetsFlutterBinding.ensureInitialized();
+
+  // 🟢 初始化 SAF 服务
+  await SafStorageService().init();
 
-void main() {
   runApp(const MyApp());
 }