fix: remove @tailwindcss/typography + fix CSS architecture

- Remove @tailwindcss/typography from package.json devDependencies
- Remove @plugin and @utility prose from globals.css
- Fix @custom-variant dark to use &:is(.dark)
- Extract @keyframes outside @supports blocks
- Scope * transition to body/body*/[class*=bg-]/[class*=border-]/[class*=text-]
- Add prefers-reduced-motion rules for scroll-to-top + reading progress
- Add :focus-visible outline on scroll-to-top

package.json

@@ -30,7 +30,6 @@
   },
   "devDependencies": {
     "@tailwindcss/postcss": "^4",
-    "@tailwindcss/typography": "^0.5.19",
     "@types/mdx": "^2.0.13",
     "@types/node": "^20",
     "@types/react": "^19",