Controls: Rewrite keyboard handler to keydrown

Also remove the `e.preventDefault();` applying to every keystroke.

Having that enabled means you cannot reload by using the keyboard (Ctrl+R) and also prevents the Inspector and Developer Console to show up.

Locate the current keyboard handler and the e.preventDefault() call, then review how keydrown should replace the existing handling. Done means keyboard shortcuts such as Ctrl+R, the Inspector, and the Developer Console work while the intended controls continue to function.

Written by the indexing model from the issue text.