dsh-ui-beautify: Change color scheme, background, and card layout for DSH Web UI

dsh-ui-beautify is a community plugin for the Web interface of DSH 0.1.1-rc.2 and later versions, maintained by Zalpha263, released under the MIT License, and supporting Windows, Linux, and macOS. This plugin aims to enhance the appearance and layout capabilities of the DSH Web UI. Its core features include toggling between light and dark modes with four color schemes (Default, Deep Sea Blue, Warm Sand, Turquoise), support for uploading and automatically compressing full-page background images (stored in localStorage with a quota of approximately 5MB), and a VSCode-style card layout system. In the card layout, sidebars, session areas, and plugin panels can be dragged to float or dock to the screen's five-way docking area. It supports adjusting width via drag handles, resizing from four sides, and auto-collapse functionality. The plugin provides a unified entry point.