Step Timeline Vertical

A vertical line draws down over 0.6s; whichever node position the line reaches, that circular node pops out, and 2 frames later the two lines of text on the right slide left and fade in (three nodes at 0.18s intervals, computed by inverting the line's easing function) — after all three groups settle, the first node upgrades into an accent-colored hollow ring scaled up 1.25x, marking "you are at this step right now"