Fix remote desktop cursor cross-contamination across dialogs

The view-mode "forbidden" cursor was applied with SetClassLongPtr(GCLP_HCURSOR),
which mutates the cursor for the whole window class instead of the single dialog
instance. Opening a second remote-desktop dialog without remote control overwrote
that shared class cursor with IDC_NO, so the already-controlled dialog also began
showing the forbidden icon even though it remained operable.

Move the view-mode cursor decision into OnSetCursor, which Windows routes per
window, and remove the now-unused class-cursor assignments. Remote-control mode
and the remote cursor-shape path are left unchanged.

Also drop the dead m_hRemoteCursor member and the leftover GetIconInfo block
(which leaked hbmMask/hbmColor in ScreenSpyDlg), plus the now-unreferenced
m_bMouseTracking flag.

Co-Authored-By: deepseek-v4-pro

server/2015Remote/HideScreenSpyDlg.h

@@ -59,6 +59,7 @@ public:
     afx_msg void OnPaint();
     afx_msg void OnSysCommand(UINT nID, LPARAM lParam);
     afx_msg void OnSize(UINT nType, int cx, int cy);
+    afx_msg BOOL OnSetCursor(CWnd* pWnd, UINT nHitTest, UINT message);
 
     virtual LRESULT WindowProc(UINT message, WPARAM wParam, LPARAM lParam);
 
@@ -75,7 +76,6 @@ protected:
     HBITMAP	            m_BitmapHandle;
     LPVOID              m_BitmapData_Full;
     LPBITMAPINFO        m_BitmapInfor_Full;
-    HCURSOR	            m_hRemoteCursor;
     CCursorInfo	        m_CursorInfo;
     BOOL                m_bIsFirst;
     BOOL                m_bIsCtrl;