Busted Beats Begone! and new "Check Beats" feature

🥁 **Busted Beats**: Story engine used to not know the difference between a Beat and a Header (text that comes before beats). Story engine has been sent to the eye doctor and given a new prescription which can tell the difference. ✅ **Check Beats**: While working on this bug, we realized it was hard to confirm which beat is which in your Prose output. Meet your new best friend - the Check Beats button! It will show you how Story Engine parses your Beats - so you can be 100% sure which beat leads to which prose. This button is well-mannered and will only appear if you actually have Beats. It's also super keen to please and will update itself in real time as you edit your Beats.