dsh-lan-guard: Securely Expose the DSH Web UI to the LAN

dsh-lan-guard is a LAN access plugin for DeepSeek Harness. It forwards the official UI to the LAN through a reverse proxy, providing self-signed HTTPS and QR code access by default. The plugin features gated reverse proxy, device pairing, blocking mechanisms, and dual password authentication. It is simple to configure, requires no source code modifications, and can be used after installation and restart.