dsh-session-control: DeepSeek Harness Sidebar Session Management

`dsh-session-control` is a DeepSeek Harness client plugin designed to optimize sidebar session management in Web mode. It takes over the sidebar body and provides features such as pinning, search, archiving, noise reduction, bulk operations, and a tagging system. The plugin supports archiving historical sessions by time period and includes a read-only viewer. It requires Node.js 20+ and a specific version of Cordis, and is intended to resolve the clutter in session lookup.