accumulateLights folded ambient+sun+torches into one accumulator clamped only
in the frag, so a few warm intensity-100 torches blew walls/objects to white.
Mirror retail SetStaticLightingVertexColors: sum point/spot into pointAcc, clamp
to [0,1] (the baked emissive), THEN add ambient+sun, frag final-clamps. Matches
LightBake.ComputeVertexColor (LightBakeConformanceTests). Per-light cap unchanged.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>