Feature: Remember host list sort preference in main dialog

Persist the sort column and direction chosen via the online host list
header (list\OnlineListSort registry key) so the next launch defaults to
the same sort. Re-apply the sort when hosts come online/offline so newly
connected hosts land in their sorted position instead of appending at the
end.

Co-Authored-By: deepseek-v4-pro

server/2015Remote/2015RemoteDlg.h

@@ -173,6 +173,9 @@ protected:
     DECLARE_MESSAGE_MAP()
 public:
     void SortByColumn(int nColumn);
+    void ApplySort();               // 按偏好重排 m_HostList（调用方需持有 m_cs）
+    void LoadSortPreference();
+    void SaveSortPreference();
     afx_msg VOID OnHdnItemclickList(NMHDR* pNMHDR, LRESULT* pResult);
     static int CALLBACK CompareFunction(LPARAM lParam1, LPARAM lParam2, LPARAM lParamSort);
     template<class T, int id, int Show = SW_SHOW> LRESULT OpenDialog(WPARAM wParam, LPARAM lParam)
@@ -342,6 +345,8 @@ public:
     std::vector<context*> m_HostList;              // 虚拟列表数据源（全部客户端）
     std::unordered_map<uint64_t, size_t> m_ClientIndex;  // clientID -> m_HostList 索引映射
     std::vector<size_t> m_FilteredIndices;         // 当前分组过滤后的索引列表
+    int  m_nSortColumn = -1;                       // 当前排序列，-1 表示未排序
+    bool m_bSortAscending = true;                  // 排序方向（true=升序）
     std::set<std::string> m_GroupList;
     std::string m_selectedGroup;
 	std::string m_v2KeyPath;                      // V2 密钥文件路径