sijidoubi/dsh-image-zoom: Markdown Image Click-to-Zoom Viewer

`sijidoubi/dsh-image-zoom` is a pure DOM plugin specifically designed for the DeepSeek Harness (DSH) web client, addressing the issue that default Markdown image thumbnails make details difficult to see. Clicking an image opens a fullscreen viewer that supports mouse-wheel zooming (100%–1200%), drag-to-pan, and fit-to-window. The plugin automatically filters out attachment thumbnails and images inside system dialogs, and is compatible with tools such as Mermaid. It works immediately after installation and is lightweight with automatic resource cleanup.