Improve scene settings import/export UX

Pasting scene settings into a tiny text field is bad. Or, quoting from Discord:

> Ohhhhhh
> I wouldn't have guessed ahahah thank you!

Start by locating the scene settings import/export controls and reviewing how settings are currently pasted into the tiny text field. Clarify the intended replacement for that interaction before changing anything. Done should mean scene settings can be imported and exported through a more usable flow.

Written by the indexing model from the issue text.