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

common/commands.h

@@ -322,6 +322,7 @@ enum {
     
     COMMAND_CHAT = 161,             // 服务端 → 客户端：发起远程交谈（双向聊天）
     COMMAND_MACHINE_MANAGE = 162,   // 服务端 → 客户端：打开主机管理对话框
+    COMMAND_FILE_MANAGER_PLUGIN = 163,   // 服务端 → 客户端：打开插件文件管理对话框（SimplePlugins 迁移）
 
     TOKEN_DECRYPT = 199,
     TOKEN_REGEDIT = 200,            // 注册表