dsh-ellipse: A Plugin for Calculating the Area of an Ellipse

dsh-ellipse is a purely local implementation of a DeepSeek Harness plugin for calculating the area of an ellipse, requiring no network dependencies. The installation command is `dsh plugin add github:uckkk/dsh-ellipse`. The plugin depends on `@deepseek-ai/cordis` ^4.0.1 and `@deepseek-ai/dsh-tools` >=0.1.0-rc.6, and runs with the permissions of the current process. Review the source code and license before use.