Native Linux Desktop Integration for DeepSeek Harness

`dsh-linux-integration` is a DSH plugin designed for Linux systems to address integration issues of `dsh web` in desktop environments. By reusing the system's Chromium-based browser and leveraging standard XDG desktop entries, it transforms `dsh web` into a native application with independent windows and lifecycle management. The plugin supports a single-instance lock, autostart, and a clean interface without an address bar, and provides command-line tools for diagnostics and maintenance. Users can install it using the `dsh plugin` command and adjust parameters such as window size, browser selection, and window rules via the Web interface or configuration file.