dsh-listing-price: Pricing Strategy Calculator

`dsh-listing-price` is a pricing-strategy-focused tool plugin in the DeepSeek Harness (DSH) ecosystem. It is a local computation tool implemented purely in Node.js with no network dependencies, designed to provide precise parameter calculation capabilities through the `listing_price` tool and address the issue of LLM computations being prone to hallucination. Developers are advised to inspect the source code before use.