WebGPURenderer: Fix runtime errors introduced by texture array refactor.

[cabanier]

It also addresses the missing render pass on layers.
cc @Mugen87

[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	549.59 152.34	549.8 152.37	+214 B +31 B
WebGPU Nodes	548.94 152.19	549.15 152.22	+214 B +30 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	467.34 112.95	467.34 112.95	-6 B -3 B
WebGPU	624.5 169.06	624.7 169.09	+208 B +26 B
WebGPU Nodes	579.35 158.35	579.55 158.38	+208 B +26 B