Sidebar Code Reference Search Tool

`dsh-sidebar-editor` is a build-free DeepSeek Harness (DSH) plugin designed to improve the document handling experience in the right sidebar. It supports colored syntax preview, workspace file search by name, and one-click quoting of selected lines or entire files into the chat box. The plugin provides right-click shortcuts in the file tree and is optimized for large files (syntax highlighting is automatically disabled for files over 4,000 lines). By default, it operates in a read-only preview mode; developers must manually enable editing and saving in `client.js`.