dsh-vacuum-buy: Vacuum Cleaner Buying Tool

`dsh-vacuum-buy` is a DeepSeek Harness (DSH) plugin for the home-cleaning domain, providing vacuum cleaner purchase solution functionality. The plugin is implemented in pure Node.js, has no external network dependencies, and depends on `@deepseek-ai/cordis` and `@deepseek-ai/dsh-tools`. After installation, it can be used in a session by invoking the `vacuum_buy` tool to obtain purchase recommendations, making it suitable for integration into DSH-based agents or applications.