UI Slider

A slider whose fill is a numeric value channel plus a thumb idle/hover/press channel (dual-channel value-channel deviation). The Slider renderer is pure (clamped 0–100 value, thumb scale, grab-ring opacity); useSliderTransition reads the frame and eases both channels — value as a numeric lerp, the thumb visual from its state presets. Muted track + primary range + bordered thumb with a derived grab ring.