dsh-official-vision: DSH Plugin for Direct Access to DeepSeek Official Vision API

`dsh-official-vision` is a DeepSeek Harness (DSH) plugin designed to connect directly to the official DeepSeek vision API without relying on third-party models. The plugin registers the `deepseek-v4-flash-vision-exp` route, supports formats such as JPEG and PNG, provides two transmission methods—Base64 inline and the Files API—and automatically passes through plain-text requests. It addresses the intermediate model dependency issue in existing vision plugins, allowing users to call DeepSeek’s multimodal capabilities directly and configure the API key, image detail level, and large-image handling options.