NodeMaterialObserver: Fix missing intensity uniform updates.

[Mugen87]

Related issue: -

Description

The PR adds the possibility to update the light map intensity in webgpu_materials_lightmap so it's easier to see the impact of a light map. That revealed a bug in the node material since only one material was updated (for the red stone).

Turns out when multiple materials share the same node builder state, uniform updates were missed because certain *intensity material properties were not racked by NodeMaterialObserver.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	337.26 78.64	337.26 78.64	+0 B +0 B
WebGPU	550.09 152.49	550.17 152.5	+75 B +13 B
WebGPU Nodes	549.45 152.33	549.52 152.34	+75 B +13 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	468.12 113.14	468.12 113.14	+0 B +0 B
WebGPU	625.46 169.27	625.54 169.28	+75 B +12 B
WebGPU Nodes	580.32 158.58	580.39 158.59	+75 B +13 B