Upgrade to Tailwind v4 (include tw-animate-css). Change both globals.css and package.json. Ensure globals.css contains shadcn :root, .dark, and @theme design tokens. Use those semantic design tokens throughout the generation, not hardcoded colors. Make any other changes as needed to migrate to Tailwind v4. Do NOT wrap :root, .dark, and @theme in "@layer base". If there are shadcn colors using just channel values, wrap them in hsl() for the new version in the :root and .dark sections (if the values are already wrapped in a color function, no need to wrap them again).