flightphp/core ? reverse-engineered prompt

Build me a small PHP micro framework called Flight that makes it easy to create fast web apps and simple REST APIs.

I want the basics to be really easy, like defining routes for different URLs, handling a homepage, and starting the app from one simple entry file. Keep it lightweight with no external dependencies, and make it work on PHP 7.4 and up. Please include a clean way to organize the framework code, some basic tests, and the usual project setup files so it feels like a real open source package people can install with Composer.

It should be simple enough for beginners, but flexible enough that people can extend it later. If you need to check current PHP best practices or docs while building it, go ahead and look them up online. Also make sure the code is solid, easy to read, and ready for a public GitHub repo.