dsh-big-clean: Pre-Holiday Cleanup

The DeepSeek Harness (DSH) plugin `dsh-big-clean` is designed for pre-holiday household preparation, specifically for the "pre-New Year deep cleaning" scenario. It provides the `big_clean` tool for generating home preparation plans. Built purely with Node.js, the plugin has no network dependencies at runtime. Developers can install it using the `dsh plugin add` command and invoke it directly within a DSH session. The plugin runs with the permissions of the current process, so it is recommended to review its source code to verify its behavior before installation.