dsh-plugin-kit: Minimal Viable Template for DeepSeek Harness Plugins

`dsh-plugin-kit` is the minimal viable function plugin template for DeepSeek Harness (DSH), designed to simplify plugin development. It packages the plugin code and configuration, is identified as a bundle layer through the `dsh.bundle.patch` field in `package.json`, and mounts the plugin using `cordis.patch.yml`. The template provides a `kit_ping` tool for liveness checking. Installation requires Node.js >= 22.14.0 and DSH 0.1.1-rc.2. Developers can customize this template by modifying the ID, renaming it, and replacing the tool logic to create their own plugin.