防止被多次初始化

(cherry picked from commit 77f1a8b30d2c30c03f0ec45fc32fe8eef9d2b4c7)

lib/singbox/service/ffi_singbox_service.dart

@@ -31,6 +31,9 @@ class FFISingboxService with InfraLogger implements SingboxService {
   late final ReceivePort _statusReceiver;
   Stream<SingboxStats>? _serviceStatsStream;
   Stream<List<SingboxOutboundGroup>>? _outboundsStream;
+  
+  /// 初始化标志，防止重复初始化
+  bool _isInitialized = false;
 
   static SingboxNativeLibrary _gen() {
     String fullPath = "";
@@ -52,6 +55,12 @@ class FFISingboxService with InfraLogger implements SingboxService {
   @override
 
   Future<void> init() async {
+    // 防止重复初始化
+    if (_isInitialized) {
+      loggy.debug("already initialized, skipping");
+      return;
+    }
+    
     loggy.debug("initializing");
     _statusReceiver = ReceivePort('service status receiver');
     final source = _statusReceiver
@@ -62,6 +71,8 @@ class FFISingboxService with InfraLogger implements SingboxService {
       source,
       const SingboxStopped(),
     ).autoConnect();
+    
+    _isInitialized = true;
   }
 
   @override