dsh-volcengine: Volcengine (Ark) Plugin Bundle for DeepSeek Harness

`dsh-volcengine` is a Volcengine plugin for DeepSeek Harness (DSH), providing model routing and tool plugins to connect to Ark models. Core features include configuring pay-as-you-go and Coding Plan routing via `cordis.patch.yml`, as well as providing the `volcengine_chat` and `volcengine_image_generate` tools. Installation supports both Web and desktop app methods, and configuration requires an API key and model ID. The plugin uses native `fetch` to call OpenAI-compatible APIs, making it lightweight and avoiding signature overhead, but desktop app dependency handling is strict, and it currently supports only Chat and text-to-image generation services.