DeepSeek Harness Plugin: dsh-tough-stain (Tough Stain)

`dsh-tough-stain` for DeepSeek Harness (DSH) is a home-cleaning utility plugin implemented purely in Node. It works without an internet connection, with its core function being to invoke the `tough_stain` tool to generate a cleaning plan for stubborn stains based on input parameters. The plugin depends on DSH core components, is open-sourced under the MIT License, and is suitable for use in restricted network environments.