dsh-user-addons: A Web Enhancement Plugin for DeepSeek Harness

The DeepSeek Harness (DSH) plugin `dsh-user-addons` is designed, following the “everything as a plugin” philosophy, to complete core features such as file processing and session management for the DSH web interface. It provides file upload (with drag-and-drop support and automatic adaptation to model capabilities), session archive management (including search and preview), a model token usage dashboard, and image capability detection. It requires no modification of core files, loads independently through DSH mechanisms, and includes Host and Web client extensions. Installation requires Node.js 22.19+, and after installation it provides API services via local routes. Plugin data is sourced from local DSH session logs, ensuring privacy and security along with a low-barrier experience for development and debugging.