codecrafters-io/frontend — reverse-engineered prompt

Build me the frontend for a CodeCrafters style web app where people learn programming by rebuilding real systems from scratch.

I want users to be able to open the app, browse programming challenges, view a challenge page with clear instructions, see their progress, and work through stages that feel like a guided learning path. The app should feel polished and developer focused, similar to app.codecrafters.io, with clean navigation, responsive layouts, and a fast experience.

Use the existing TypeScript and Ember setup for the project. Make sure it can run locally with Bun, connect to a backend URL from environment variables, and work against a staging backend if needed. Include sensible loading states, error states, and test friendly structure. Keep the implementation practical and close to what this repo is already set up for.

Look up current docs online if you need to, then get it running and make sure the main pages build without obvious issues.