dsh-file-manager: File Management and Editing Views for DeepSeek Harness Web

`dsh-file-manager` is a Web plugin for DeepSeek Harness (DSH) that provides file management for Web Sessions by integrating the Monaco editor. It supports file tree browsing, multi-tab editing, syntax highlighting, and multi-language support. The plugin is strictly confined to the authoritative directory of the current Session and uses atomic save mechanisms to prevent version conflicts. Installation requires meeting the necessary Node.js version requirements and enabling the plugin via the `dsh plugin` command, making it suitable for viewing and editing code directly in a Web environment.