Extends the cross-backend RT type surface for procedural geometry +
any-hit on the WebGPU path:
- RTShaderGroupType::ProceduralHitGroup + RTShaderGroup::intersectionShader
(mirror VK_RAY_TRACING_SHADER_GROUP_TYPE_PROCEDURAL_HIT_GROUP_KHR).
- WebGPURTStage::Intersection for AABB intersection shaders.
- Mesh::BuildProcedural(span<RTAabb>, opaque) — the WebGPU analog of a
VK_GEOMETRY_TYPE_AABBS_KHR geometry.
- wgpuRegisterMeshBLAS gains geomType / opaqueFlag / primCount.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
