dsh-client-ui-tweakcn: Map tweakcn.com's index.css to DSH theme

dsh-client-ui-tweakcn is a DSH client theme plugin maintained by AIRIKE1 (MIT License), aiming to address issues such as missing token mappings when directly modifying styles and the inconvenience of switching between multiple themes. The plugin supports pasting the `index.css` exported from tweakcn.com into DSH to automatically map semantic tokens for color schemes, border radius, shadows, and fonts, and allows for saving, switching, editing, or deleting multiple theme sets. Its features cover oklch/hsl/hex color parsing, light/dark mode adaptation, standardized mapping of border radius and shadow variables, and error prompts to prevent the accidental pasting of `layout.tsx`. The plugin adopts a local-first strategy and does not impede DSH startup in the event of errors. Installation methods include searching for and installing from the plugin market, and executing...