The b == 0 branch now guards t1 != t0 like the sloped branch (C# and both HLSL
copies), so an infinite bound times a zero length no longer forms NaN.
Edge-grid mirror test and a counting-clamp shadow test replace the text-order
check; the four pin tests assert equality with their measured expression;
tools/compile-hlsl.ps1 is the one dxc compile verdict for the HLSL copies.
Builds. CultMath.glsl and glsl-parity.json are not yet regenerated, so
CommittedGlslEqualsLowering and GoldenFixtureMatchesCSharp are red at this
commit; the next commit regenerates them.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
