dsh-explorer-editor: A VS Code-Style File Manager for DeepSeek Harness

The `dsh-explorer-editor` plugin provides a VS Code-style file management experience for DeepSeek Harness Web. It displays the file tree on the left and offers code editing via the Monaco editor in the center, with support for switching between Markdown source and preview. It includes file tree navigation, context menus, theme customization, and automatic encoding detection. File state is persisted using local storage, and the directory tree is refreshed in real time through SSE. Installation requires running the command under the corresponding profile, while security boundaries are controlled in the configuration via `root` and `allowArbitraryRoot`.