Improve: Show host remark instead of IP in remote desktop dialog titles

When an online host has a remark set in the client list, use it in place of
the IP in the remote desktop ("远程桌面控制") and virtual screen ("远程虚拟屏幕")
dialog titles, falling back to the IP when no remark is present.

Add a GetTitleHostName() helper to both dialogs. CScreenSpyDlg resolves the
remark through its parent dialog's client map, while CHideScreenSpyDlg uses
the global g_2015RemoteDlg pointer; each falls back to m_IPAddress when the
host has no remark.

Co-Authored-By: deepseek-v4-pro

server/2015Remote/ScreenSpyDlg.h

@@ -234,6 +234,9 @@ public:
     // fillMode: 0=不填充, 1=全黑, 2=半透明
     VOID DrawTipString(CString strString, int fillMode=1);
 
+    // 标题栏显示的主机名：有备注用备注，否则用 IP
+    CString GetTitleHostName() const;
+
     POINT  m_ClientCursorPos;
     BYTE m_bCursorIndex;
     BOOL     m_bIsTraceCursor;