dsh-plugin-template: DSH Plugin Development Scaffolding

`dsh-plugin-template` is a client-side plugin development scaffold for DeepSeek Harness (DSH), designed to simplify the creation of new tool plugins. It features a pure ESM architecture, a zero-dependency and build-free design, and built-in scaffolding scripts. Developers can quickly generate a project skeleton using the scripts, then configure files and implement overrides according to the guide to enable local validation and npm publication. This template is especially suitable for developers who want to set up DSH plugins quickly.