UOverlayElement backdrop (0.2s ease) and UDrawer panel (0.55s easeOutExpo)
had mismatched durations/easings causing a "boing" visual artifact on
open/close. Unify both to 0.35s cubic-bezier(0.25, 1, 0.5, 1) easeOutQuart.

Also fix exports map (src/* → dist/*) so consumers resolve built artifacts.

Bump to 1.0.3.