Brings Fix C (57c1135, sun-vector magnitude / ~32% over-bright) + the A7 lighting
handoff doc onto main. Auto-merged clean against the D.2b line. Merged tree builds
green; 18/18 sky tests pass. Fix A/B already on main (37911ed).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>