dsh-public-proxy: Expose DSH Web UI to the LAN

dsh-public-proxy is a DeepSeek Harness (DSH) plugin maintained by SpringNyan, intended to address restricted local-area network access during local debugging. By modifying underlying configuration settings, the plugin exposes the DSH Web UI to devices on a local network, listening on port 3081 by default. Users can install it with the `dsh plugin` command. The plugin supports custom ports, Host settings, and access control, and allows configuring Cookie authentication or bypassing the startup token to strengthen security. However, it binds the Host to `0.0.0.0`, which means the Web UI is exposed to the entire network and served over unencrypted HTTP. Therefore, it should only be used in a trusted local-area network environment and must never be exposed to the public internet.