dsh-plugin-pin-session: Pin DeepSeek Harness Session

`dsh-plugin-pin-session` is a DeepSeek Harness plugin maintained by NattoCB, designed to address inefficient management of long session lists. The plugin adds a fixed “Pinned Sessions” group at the top of the sidebar and integrates Pin/Unpin actions inline, enabling quick location and management of sessions. Its core features include inline actions, grouped display, and cross-browser persistent storage based on the host-side file system, while remaining fully non-intrusive to the core codebase. Installation must be performed via the command line and requires restarting the DSH process to take effect. It supports operations through the HTTP API and is suitable for developers who frequently switch between specific sessions.