chore: Add CLAUDE.md, TODO.md, and fix ReadBooks Tailwind classes

- Add CLAUDE.md with project architecture, conventions, and common tasks
- Add TODO.md with prioritized roadmap (book reviews, CMS, n8n, frontend)
- Fix invalid Tailwind classes in ReadBooks.tsx (h-30 -> h-[7.5rem], w-22 -> w-24)

https://claude.ai/code/session_017E8W9CcHFM5WQVHw74JP34

app/components/ReadBooks.tsx

@@ -133,7 +133,7 @@ const ReadBooks = () => {
                 transition={{ duration: 0.5, delay: 0.2 + index * 0.1 }}
                 className="flex-shrink-0"
               >
-                <div className="relative w-20 h-30 sm:w-22 sm:h-32 rounded-lg overflow-hidden shadow-lg border-2 border-white/50">
+                <div className="relative w-20 h-[7.5rem] sm:w-24 sm:h-32 rounded-lg overflow-hidden shadow-lg border-2 border-white/50">
                   <img
                     src={review.book_image}
                     alt={review.book_title}