RenderObject: Fix geometry key for morph targets.

[Mugen87]

Fixed #30192

Description

RenderObject.getGeometryCacheKey() must honor morph target attributes. However, a simple structural comparison like with normal buffer attributes isn't sufficient. Since the vertex data are maintained in a texture via MorphNode, render objects can only share a common node builder state if morph target data are equal. That is verified with a new id attribute on BufferAttribute level.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	339.52 79.1	339.52 79.1	+0 B +0 B
WebGPU	490.99 136.33	491.07 136.35	+84 B +14 B
WebGPU Nodes	490.45 136.22	490.54 136.24	+84 B +15 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	465.36 112.15	465.41 112.15	+55 B +8 B
WebGPU	560.28 151.74	560.42 151.75	+139 B +13 B
WebGPU Nodes	516.38 141.53	516.52 141.57	+139 B +44 B

[sunag]

Thanks @Mugen87 . I was working on this the last few days too. Your solution is great, maybe in the future we can update the texture uniform dynamically from getEntry() if the position, normal etc match, to take advantage of the cache.