dsh-image-amnesia: DeepSeek Harness Vision Offloading Plugin

dsh-image-amnesia is a DeepSeek Harness plugin designed to resolve issues where relay gateways crash due to an excessive number of historical images (approximately 20MB or 600 images by default). Before sending a request, the plugin automatically discards older images and retains only the latest `keepAtLeast` images, thereby optimizing resource usage and preventing crashes. It supports global override, takes effect after a single installation, and preserves native vision capabilities while reducing token consumption. Users can adjust the retention policy through configuration, and local storage is not affected.