384bfecf3a
16 easing curves (linear, quad, cubic, expo, elastic, bounce in/out/inOut) header-mostly so the compiler inlines on hot paths. Pure, no I/O, no state. Includes: - tween::apply(Ease, t) dispatcher for data-driven uses (timeline keyframe.ease, dropdown selection) - tween::name(Ease) for UI labels - tween::ease_count for iteration Tested values documented in tween_curves.md.