ArthurSonzogni/FTXUI ? reverse-engineered prompt

Build me a clean, modern C++ terminal UI library for making interactive text based apps.

I want it to feel simple and pleasant to use, with a reactive style so I can compose screens from small pieces, add buttons, menus, text boxes, gauges, and layouts, and handle keyboard and mouse input without a lot of boilerplate. It should work nicely in a normal terminal on Linux and macOS, and ideally also support Windows and WebAssembly. Please include styling like colors, bold, borders, and basic animations, plus support for UTF 8 and full width characters.

Make it easy to use from a single header if possible, but also keep the library organized so the low level rendering, layout, and interactive widgets are separated. Include a few runnable examples and a simple build setup so someone can try it quickly with CMake, and look up current docs online if you need to.