Harden CUDA rasterization near degeneracies (#1710)

Summary:
Pull Request resolved: #1710

Condition CUDA triangle coverage when the projected determinant is poorly conditioned. Triangle setup widens determinant and edge construction to FP64, rejects numerically degenerate triangles, evaluates fragile edges in clipped-bounding-box-local coordinates with split FP32 coefficients and per-row intercepts, and leaves the existing FP32 pixel path unchanged for well-conditioned triangles.

Clamp projected bounds before integer conversion and reject overflowing FP32 fast-path determinants so malformed finite inputs cannot shade an entire image.

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landed-with-radar-review

Differential Revision: D127295006

fbshipit-source-id: f7d38c2270ed7fb83ba8e49f5a1ecc80a47fee60

Author: cdtwigg