2.1b: engine update

hi! mini 2.1b is out with some real quick fixes:

• we updated SDL to 3.2.4, which in practice means that most platform bugs should be gone, including the unstuck mouse bug on Windows, and hopefully the memory leak on certain macOS machines.
• the state editor is now open by default, which is mostly to get beginners to understand where the image buttons are. hopefully this doesn't bother you <3

that's it! we're focusing on the full version and on revamping the website, so no big mini updates for a while. thank you for using the program!