[Feature] 添加 Skill 系统，放在设置标签页下；允许动态加载 SKILL / Add Skill System Under Settings Tab with Dynamic Loading of SKILLs

[SunYanbox]

• 在设置标签页中增加“Skill 系统”子面板，用于管理可插拔的 SKILL 模块。
  Add a "Skill System" sub-panel under the settings tab to manage pluggable SKILL modules.

• 支持动态加载 SKILL：用户可将 SKILL 文件/文件夹放入指定目录，系统自动识别并加载，无需重启主程序（或仅需热重载）。
  Support dynamic loading of SKILLs: users can place SKILL files/folders into a designated directory, and the system automatically detects and loads them without restarting the main application (or with hot-reload only).

• 设置标签页需展示已加载 SKILL 列表、提供启用/禁用、卸载、重新加载等操作按钮。
  The settings tab must display a list of loaded SKILLs and provide actions such as enable/disable, unload, and reload.