shadcn-ui/taxonomy ? reverse-engineered prompt

Build me a polished open source style website that feels like a modern Next.js app, with a public marketing site, a docs section, a blog, and a few protected areas for signed in users. I want authentication, a simple subscription flow, and pages that show loading states nicely while content is being fetched. The site should have a clean component based UI, support dark mode, and look good on mobile and desktop.

Use current best practices where you can, and if anything in the framework has changed since the original idea, look up the latest docs online and follow that instead. Make it feel like a real product, with reusable layouts, good navigation, metadata for pages, and a nice reading experience for articles written in MDX.