dsh-read-image-view: Directly display images read by read_image in DSH Web GUI

dsh-read-image-view is a pure client-side plugin designed specifically for the DSH Web GUI, developed by Yu-tao-Li and licensed under the MIT license. This plugin aims to address the issue where users cannot directly preview images after a model call to `read_image`, thereby enabling the direct display of images within the conversation flow. Its core features include automatically expanding to display `Read image` results, supporting a gray-white checkerboard background for transparent images, and merging multiple images from the same request into a side-by-side display. Furthermore, the plugin provides an in-page zoom layer that supports zoom buttons, scroll wheel zooming, and 1:1 original size viewing. The plugin features zero runtime dependencies, does not modify the DSH core, does not introduce new network endpoints or perform file I/O operations, and relies solely on `session/atta...