DeepSeek Harness Fork to Preset Plugin

`dsh-fork-to-preset` is a modular plugin for DeepSeek Harness designed to simplify session switching in agent development. The plugin adds a “Fork to preset” button to the conversation title bar via the UI, allowing users to fork the current session into a new agent preset, inherit the history, and generate an independent sub-session. Because it is not published to npm, it requires manual directory linking and Profile file configuration. The plugin requires Harness rc.8 or later and is available only on GitHub.