DeepSeek Harness dual-face plugin: session-isolated file upload with colorful composer cards + read_document tool (text/PDF/DOCX/XLSX) with content sniffing and LRU caching

向模型暴露 MinerU 文档解析工具，将 PDF/图片/DOCX/PPTX/XLSX 转为结构化 Markdown/JSON | Exposes MinerU document-parsing tools to the model, converting PDF/images/DOCX/PPTX/XLSX into structured Markdown/JSON

Office document tools (xlsx / pdf / pptx / docx) for DeepSeek Harness: generate, read, and edit spreadsheets, PDFs, presentations, and Word documents