dsh-btu2kj: BTU to Kilojoules

`dsh-btu2kj` is a DeepSeek Harness (DSH) plugin developed by uckkk, providing local physical unit conversion from BTU to kilojoules. The plugin is implemented entirely in Node.js, has no network dependencies, and is lightweight and secure. Users can install it via a terminal command, making it suitable for offline physical unit conversion scenarios. Review the source code and license before installation.