dsh-image-preview: Inline Preview Providing the `read_image` Tool for DeepSeek Harness

The `dsh-image-preview` plugin takes over the tool rendering slot in DeepSeek Harness (DSH) to provide inline previews and image-copying support for the `read_image` tool. It supports direct and nested calls, such as Code Mode, converts image formats such as JPEG/WebP/GIF to PNG for copying, and uses authenticated attachment paths for secure rendering. Installation requires DSH 0.1.2-alpha.2. Once enabled, you can view images directly in the interface or copy them via a button. The plugin is open source under the MIT license and is suitable for developers who need to visually display and handle images in DSH.