feat: add glTF shape geometry and culling

[ibgreen]

Summary

• add a renderer-independent @math.gl/geometry package with typed-array Geometry storage, indexed unpacking, and tessellators for the glTF box, capsule, cylinder, plane, and sphere shapes
• port/adapt the basic luma.gl convenience primitives: cube, cone, truncated cone, and icosphere
• add matching BoxShape, CapsuleShape, CylinderShape, PlaneShape, and SphereShape analytic volumes to @math.gl/culling
• document the new module and shape-query API, including luma.gl/TDL attribution

Semantics and scope

The defaults and coordinate conventions follow the active glTF 2.1 draft at KhronosGroup/glTF@726e078.

The geometry package is CPU-only and uses glTF attribute semantics (POSITION, NORMAL, TEXCOORD_0); it has no luma.gl/GPU dependency. PlaneGeometry requires finite dimensions because an infinite surface cannot be tessellated.

The culling shapes support point containment/distance, plane and CullingVolume classification, nearest ray hits, invertible affine transforms, AABBs, and conservative bounding spheres. PlaneShape preserves the glTF negative-Y inside half-space and supports finite, partially infinite, or infinite surface extents. Distance is exact for rigid/uniform transforms and estimated for non-uniform scale or shear. Pairwise shape-vs-shape collision and glTF JSON parsing are intentionally out of scope.

Verification

• yarn build
• yarn lint
• yarn test node — 3,205 assertions passing
• yarn --cwd website build
• repository pre-commit hook (lint + full Node suite)

Tests cover defaults and validation, tapered/contained capsules, finite and partially infinite planes, point/distance/ray/plane/frustum queries, affine transforms, bounds, 16/32-bit indices, attribute finiteness, winding, and tessellated-mesh parity with analytic shapes.