Yay! Runestone now works with... *Checks notes*... UIKit?? 🤨

In order to prepare for AppKit support, I had to rip the internals of Runestone apart and put it together again. For the first time in 36 hours, Runestone now works with UIKit again.

So I now have an NSWindow with an NSView that receives keystrokes. That's like step 0 in building a text editor, right?

There's such a long way to go still before Runestone is rewritten in AppKit. I hope I'll eventually turn a corner where all my work from UIKit can be reused and I ✨magically✨ have an AppKit implementation.

The AppKit version of Runestone now supports scrolling the content.

This involves a bit more than just wrapping everything in an NSScrollView because Runestone only renders the lines within the viewport.

Baby steps, y'all.