SOFT_SHADOWS

Soft shadows: true = 3x3 nine-tap PCF kernel; false (default) = a single depth-compare tap whose free 2x2 hardware bilinear still softens the edge one texel. The nine-tap kernel is the dominant shadow fragment cost on mobile (~55% of shadow GPU time measured), so it's opt-in. Baked into receiver shaders - assign before the first frame, like SHADOW_CASCADE_MAP_SIZES.