dsh-theme-macintosh: DSH Classic Macintosh Theme Plugin

The DSH Classic Macintosh theme plugin (by fengb3) aims to render the DeepSeek Harness interface in the pixel-art style of System 7. It features a persistent top menu bar, a complete pixel-style reskin (covering the conversation flow, reasoning cards, input dock, and more), light and dark modes, and a Kit inspector. Installation is recommended via the official command-line tool; after installing, refresh the page to apply the changes, with no additional build steps required.