Do Puzzle Name validation within AddPuzzleModal and report to user within pop-up instead of as separate error

[maximized]

When you enter a puzzle name that is too long, you don't find out about the error until you have clicked to create the puzzle. The error message appears at the top of the puzzle list page. If instead, we truncated the input box or alerted the user within the dialog panel, users could correct it before submission to avoid having to re-enter the information after seeing the error.