Motion draft v0.2.0

Durations and easing curves, the state transitions of controls, and how motion gives way when people ask for less of it.

Motion holds two durations and one easing curve, the design system's additions (packages/tokens/src/additions/): the Figma library has none. Components read them directly for one use: the transition of a control between its states. Every transition is a color change, never a movement, and every component switches it off when people ask for reduced motion.