fix(Network): 移除未实现的Close方法并修正SystemTcpNetworkChannel中的Close调用

在NetworkChannelBase中移除未实现的Close方法，避免潜在异常。在SystemTcpNetworkChannel中修正Close方法的调用，添加正确的关闭原因和错误码参数。

Author: AlianBlank

Runtime/Network/Network/NetworkManager.NetworkChannelBase.cs

@@ -769,11 +769,6 @@ public async Task<TResult> Call<TResult>(MessageObject messageObject) where TRes
                 return result as TResult;
             }
 
-            public void Close()
-            {
-                throw new NotImplementedException();
-            }
-
             /// <summary>
             /// 向远程主机发送消息包。
             /// </summary>

Runtime/Network/Network/SystemSocket/NetworkManager.SystemTcpNetworkChannel.cs

@@ -376,7 +376,7 @@ private void ConnectCallback(IAsyncResult asyncResult)
                 {
                     SocketException socketException = exception as SocketException;
                     NetworkChannelError?.Invoke(this, NetworkErrorCode.ConnectError, socketException?.SocketErrorCode ?? SocketError.Success, exception.ToString());
-                    Close();
+                    Close(NetworkCloseReason.ConnectClose, (ushort)(socketException?.SocketErrorCode ?? SocketError.Success));
                     return;
                 }