dsh-gsd-bridge: Mounting GSD Core as a Native Slash Command in DeepSeek Harness

The `dsh-gsd-bridge` plugin for DeepSeek Harness leverages in-memory adapter technology to map GSD Core's specification-driven workflows to `/gsd-*` slash commands, enabling seamless “zero fork” integration. It supports 71 workflow commands and offers core capabilities including session targeting, automatic state reading, and swappable project state. When installing, be aware of dependency issues in DeepSeek Harness's RC stage. With this plugin, users can directly invoke GSD's `Discuss → Plan → Execute` loop in the DSH Web UI, enabling agile, specification-driven development.