fuma-nama/fumadocs ? reverse-engineered prompt

Build me a beautiful, flexible docs website framework for React apps and Astro. I want it to make it easy to create a polished documentation site with a nice landing page, docs pages, navigation, search friendly content, and support for writing pages in MDX. It should work well with Next.js, Astro with React, and modern Vite based setups like TanStack Start and React Router. Keep it clean, fast, and easy to customize so teams can make it feel like their own site without fighting the setup.

Please make the experience smooth for both developers and content writers, and keep the codebase modern with TypeScript and ESM only. If you need to check current docs or integration details for any of the supported frameworks, look them up online and adapt the implementation accordingly.