Roost examples

• Playground: write a module, run it, and try it in a REPL, in the page (source)
• Counter: use-state, use-effect, DOM events (source)
• Router and Query: React Router and TanStack Query from Scheme (source)
• TodoMVC: the TodoMVC application (source)
• Checkout: a store page with a 200-product catalog, cart, and validated checkout form (source)