da-luce/astroterm — reverse-engineered prompt

Build me a terminal planetarium app in C called astroterm. I want to open it in a terminal and see an ASCII sky map showing the real time positions of stars, planets, the moon, and constellations, with optional color and nicer Unicode characters when the terminal supports them. It should let me set a date and time, choose my location by latitude and longitude or by city name, and tweak things like brightness cutoff, labels for bright stars, animation speed, frames per second, aspect ratio, a sky grid, metadata, and whether constellation lines are shown.

Please make the moon phase accurate and keep the whole thing lightweight and fast enough to use like a little screensaver. I would also like a simple help screen with the available flags, Bash tab completion, and clear install or build and run instructions for Linux, macOS, and Windows if possible. It should feel polished in the terminal, easy to try right away, and quit cleanly with a keypress. If you need details, look up the current docs online.