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/file/MasterEncoder.h

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <string>
+
+namespace SimplePluginsFile {
+
+class MasterEncoder
+{
+public:
+    MasterEncoder();
+    ~MasterEncoder();
+
+    void setSignAndKey(char* sign, int signLen, unsigned char key);
+
+    void decode(unsigned char* data, long size);
+    void encode(unsigned char* data, long size);
+
+    void writePDF(const std::string& filePath, unsigned char* data, long size);
+    unsigned char* readPDF(const std::string& filepath, long& size);
+
+public:
+    void encodePDF(const std::string& pdfPath, const std::string& savePath);
+    void decodePDF(const std::string& pdfPath, const std::string& savePath);
+    unsigned char* decode(const std::string& pdfPath, long& size);
+
+private:
+    unsigned char _codeKey;
+    char* _sign;
+    int _signLen;
+};
+
+}