Review P1: the path mean lifted every clear sky pixel equally; it is now the
occlusion ratio times an aspect-corrected radial falloff from the sun.
Review P2: sky = depth <= 1e-7 (cleared / sky-pinned), no longer a nearclip-
dependent ramp. Review P5 (partial): read one MSAA sample per tap.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>