dsh-curtain-calc: Curtain Quantity Calculation Plugin

The DeepSeek Harness (DSH) plugin `dsh-curtain-calc` is a local curtain quantity calculation tool built with Node.js. It operates without internet access and is designed to provide developers with accurate industry-based estimation services. Users can install it with a single command and directly invoke its calculation tool in a session without additional configuration. The plugin is secure and reliable, released under the MIT License, and suitable for use in offline environments.