nwhirschfeld/ctfEngine ? reverse-engineered prompt

Build me a small CTF web app that can host a handful of players for onsite events or classes.

I want it to run as one simple service in a container, with no external database setup, and to load a CTF from a folder on disk. The CTF should have a main config file plus per challenge folders, each with its own config, optional files, optional Dockerfile, and things like name, description, points, flag, category, hints, and service port.

The app should let users sign up and log in, browse the list of challenges, open a challenge page, view any attached files, submit flags, and see their score. It should also support a signup token option so I can make registrations invite only.

Please make it feel like a complete batteries included CTF platform, with a clean frontend and backend in one app, and include a sample CTF so I can test it right away. If you need to check current docs for any Go libraries or best practices, feel free to look them up online.