Review the old build process

[cyberMilosz]

Our current build process is a mess. It doesn't correctly declare executable scripts (especially impactful on Windows, since we basically need a .bat file to run Python lmao), it relies on running setup.py as a script (apparently a no-no), it introduces silly bugs, and makes working with IDEs clunky.

Probably needs a rewrite as a TOML config file for setuptools. Leaving this one to Alex because they know what they're doing