Feature: Add get/set clipboard buttons to remote desktop toolbar

Add two toolbar buttons — get clipboard (letter C) and set clipboard (letter P) —
after the screenshot button and before the minimize button, so clipboard sync stays
reachable in fullscreen mode where the system menu cannot be opened.

The buttons reuse the existing IDM_GET_CLIPBOARD / IDM_SET_CLIPBOARD system-menu
handlers by posting WM_SYSCOMMAND to the parent. The toolbar button count grows
from 16 to 18, and the slide/animation dimensions are widened from 640 to 720.
Letter C/P icons and Simplified-Chinese source strings ("获取剪贴板", "设置剪贴板")
are added, along with English and Traditional-Chinese translations.

Co-Authored-By: deepseek-v4-pro

server/2015Remote/CIconButton.cpp

@@ -551,6 +551,18 @@ void CIconButton::DrawIconLetterZ(CDC* pDC, const CRect& rc)
     DrawLetterIcon(pDC, rc, _T("Z"));
 }
 
+// Letter C icon (获取剪贴板)
+void CIconButton::DrawIconLetterC(CDC* pDC, const CRect& rc)
+{
+    DrawLetterIcon(pDC, rc, _T("C"));
+}
+
+// Letter P icon (设置剪贴板)
+void CIconButton::DrawIconLetterP(CDC* pDC, const CRect& rc)
+{
+    DrawLetterIcon(pDC, rc, _T("P"));
+}
+
 // Audio On: speaker with sound waves
 void CIconButton::DrawIconAudioOn(CDC* pDC, const CRect& rc)
 {