SkinnedMesh: Update "applyBoneTransform" to optionally take Vector4, support direction or position transformation

[gkjohnson]

Related issue: --

Description

Previously there was no way to transform directions like vertex normals or tangents with SkinnedMesh. This PR updates the "applyBoneTransform" to take both a Vector3 or a Vector4. If a Vector3 is passed then it is assumed to be a position vector, as before. If a Vector4 is passed then homogenous coordinates can be used to treat it as either a direction (w === 0) or a position (w === 1).

Adjustment made for SkinnedMesh support in the path tracer.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	359.57 85.37	359.57 85.37	+0 B +0 B
WebGPU	626.97 174.23	626.97 174.23	+0 B +0 B
WebGPU Nodes	625.55 173.98	625.55 173.98	+0 B +0 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	491.31 119.78	491.31 119.78	+0 B +0 B
WebGPU	700.59 189.23	700.59 189.23	+0 B +0 B
WebGPU Nodes	649.8 176.59	649.8 176.59	+0 B +0 B