dsh-plugin-sidebar-manager: Category Management and Plugin Start/Stop in DSH Web Sidebar

# Introduction DSH adopts a "everything is a plugin" architecture. As system-built plugins and user-installed plugins accumulate over time, the list grows. In the Web UI, the entry point to view and manage these plugins is located at "Settings -> Plugins". This requires navigating to the settings page every time just to check what has been installed and which are currently running. `dsh-plugin-sidebar-manager` addresses this workflow issue by placing a "Plugins" button directly in the Web UI's left sidebar. Users can click to browse plugins by category, search for them, and start or stop user-added plugins at runtime. The following sections introduce its features, installation methods, and underlying mechanism. # What is it One-sentence definition: It adds a "Plugins" button to the DSH Web UI left sidebar, categorizes and displays system-built and user-added plugins, and supports