Consolidate duplicate numeric-vector type predicates into TypeSemantics

[NripeshN]

Summary

Round 2 of the type-predicate consolidation started in #33. Three files each carried their own copy of the "numeric vector" predicate:

• HIR.cpp::isNumericVectorTypeName
• HIRPassManager.cpp::isHIRNumericVectorTypeName
• Intrinsics.cpp::isNumericVectorType

All three enumerated the same set (vec / ivec / uvec × {2,3,4}, excluding the boolean bvecN). They are replaced by a single canonical crossgl::isNumericVectorTypeName in TypeSemantics, defined in terms of the existing canonical isVectorType so the numeric-vector set stays in lock-step with the vector set:

bool isNumericVectorTypeName(std::string_view name) {
  // Vector types with numeric components: every vector type except the boolean
  // vectors (bvecN).
  return isVectorType(name) && !name.starts_with("bvec");
}

This removes the last of the hand-maintained vector-type literal lists outside TypeSemantics, eliminating a class of drift bug (the three copies could silently disagree if a new vector type were ever added).

Verification

Full suite green: 100% tests passed, 0 tests failed out of 2452.