[idd] lgmp: use precise clipboard polling

Drive adaptive clipboard stream polling with a high-resolution waitable
timer instead of rounding microsecond delays into coarse wait-function
timeouts.

Preserve the explicit stop and local wake events while avoiding a clock-tick
stall at each file-transfer window.

idd/LGIdd/transport/lgmp/CLGMPClipboardTransport.h

@@ -114,6 +114,7 @@ private:
   IClipboardTarget * m_target = nullptr;
   HANDLE m_stopEvent = nullptr;
   HANDLE m_wakeEvent = nullptr;
+  HANDLE m_pollTimer = nullptr;
   HANDLE m_thread    = nullptr;
 
   bool m_available          = false;