防止被多次初始化

(cherry picked from commit 77f1a8b30d2c30c03f0ec45fc32fe8eef9d2b4c7)

lib/app/services/singbox_imp/kr_sing_box_imp.dart

@@ -99,6 +99,9 @@ class KRSingBoxImp {
   /// Stream 订阅管理器
   final List<StreamSubscription<dynamic>> _kr_subscriptions = [];
 
+  /// 初始化标志，防止重复初始化
+  bool _kr_isInitialized = false;
+
   /// 当前混合代理端口是否就绪
   bool get kr_isProxyReady => kr_status.value is SingboxStarted;
 
@@ -131,6 +134,12 @@ class KRSingBoxImp {
 
   /// 初始化
   Future<void> init() async {
+    // 防止重复初始化
+    if (_kr_isInitialized) {
+      KRLogUtil.kr_i('SingBox 已经初始化，跳过重复初始化', tag: 'SingBox');
+      return;
+    }
+    
     try {
       if (_initialized) {
         KRLogUtil.kr_i('SingBox 已经初始化，跳过重复初始化');
@@ -249,9 +258,12 @@ class KRSingBoxImp {
       });
 
       KRLogUtil.kr_i('SingBox 初始化完成');
+      _kr_isInitialized = true;
     } catch (e, stackTrace) {
       KRLogUtil.kr_e('SingBox 初始化失败: $e');
       KRLogUtil.kr_e('错误堆栈: $stackTrace');
+      // 如果初始化失败，允许下次重试
+      _kr_isInitialized = false;
       rethrow;
     }
   }