dsh-ws-files: Workspace File Browser

`dsh-ws-files` is a plugin for DeepSeek Harness (DSH) that integrates a file tree, search, and an online editor into the DSH layout. It supports lazy loading, search, online editing (with real-time highlighting, indentation, auto-save, and undo/redo), and multi-workspace switching. The plugin is implemented with a Host/Client architecture and enforces strict security constraints: all read and write operations are restricted to registered workspace directories to ensure safety. Users can install it via the command line and manage local code directly through the Web interface.