WebGPURenderer: Rename Nodes to NodeManager

[sunag]

Description

We already have a file called Nodes.js used for exporting the Nodes, which can cause conflicts when referencing files or classes.
The new name NodeManager should preserve the functionality of the class.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	355.82 84.56	355.82 84.56	+0 B +0 B
WebGPU	621.5 172.57	621.5 172.57	+0 B +0 B
WebGPU Nodes	620.1 172.33	620.1 172.33	+0 B +0 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	488.06 119.45	488.06 119.45	+0 B +0 B
WebGPU	691.97 187.85	691.97 187.85	+0 B +0 B
WebGPU Nodes	641.77 175.02	641.77 175.02	+0 B +0 B