dsh-harvest: DSH Native Multi-Platform Research Pipeline Plugin

The DeepSeek Harness plugin `dsh-harvest` is a plugin-based tool for research and analysis scenarios, automating multi-platform research through a `scout → extract → verify → audit` pipeline. It supports 11 channels, including GitHub, the web, and social media, and features a fault-tolerant fallback mechanism. The plugin depends on multiple CLI tools and has specific compatibility requirements when running on Windows, macOS, and Linux, requiring configuration of the Python path, cookies, and API keys. Users can install it from the native DSH marketplace to perform broadcast discovery, in-depth research, and source auditing, aiming to reduce the complexity of agent research.