dsh-tip-calc: Tip Calculator

The DeepSeek Harness (DSH) plugin `dsh-tip-calc` provides a pure Node.js implementation for tip calculation. It supports precise, parameter-driven calculations and returns detailed results without making network requests. Developers can install it in the DSH environment via command-line installation. It requires the `@deepseek-ai/cordis` and `@deepseek-ai/dsh-tools` dependencies. The plugin is open source under the MIT license, and it is recommended to review the source code before installing.