dsh-codex-pins: DeepSeek Harness Sidebar Session Pinning Plugin

The DeepSeek Harness plugin `dsh-codex-pins` follows Codex’s design philosophy by splitting the sidebar into two independent panels, Pinned and Recents, addressing the difficulty of finding items caused by the default mixed view. The plugin is implemented entirely in the UI, supports persistent data storage, allows up to 50 pinned sessions, and provides data import from previous plugin versions. Users can manage pinned sessions by hovering over or clicking the pin icon in the title bar. After installation, restart the application to enable it.