dsh-open-file: DeepSeek Harness Web workspace file attachments and reading plugin

dsh-open-file is an open-source plugin for DeepSeek Harness Web designed to solve local file processing challenges by providing file attachments, document reading, local OCR, and page rendering capabilities within the workspace scope. The plugin supports uploading files via file picker, drag-and-drop, or clipboard, and saves them to the current session workspace to avoid information loss caused by manual pasting. Core features include four Agent tools: `file_inspect` for obtaining metadata, `file_read` for reading text or table content, `file_ocr` supporting English and Simplified Chinese local recognition, and `file_render` capable of rendering document pages into PNG images. The plugin is compatible with Windows, Linux, and macOS, and requires Node.js.