Renderers: Disable bump mapping for wireframe rendering.

[mrdoob]

Related issue: #31242

Description

While working on #33776 I noticed that some models renderer black in wireframe mode.

Turns out bumpMap was the culprit.

Bump mapping relies on screen-space derivatives, which are unreliable on thin lines — bump-mapped materials render mostly black in wireframe.

Disables the bump perturbation when material.wireframe is true, in both BumpMapNode and WebGLPrograms. Same approach as #31242, which gated flatShading (also derivative-based) for the same reason — including the same compromise: toggling wireframe at runtime requires material.needsUpdate = true.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	365.48 86.82	365.5 86.83	+18 B +4 B
WebGPU	666.43 184.37	666.47 184.38	+40 B +13 B
WebGPU Nodes	664.47 184.06	664.51 184.07	+40 B +13 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	507.44 123.35	507.46 123.35	+18 B +5 B
WebGPU	745.68 200.56	745.72 200.58	+40 B +11 B
WebGPU Nodes	694.9 188	694.94 188.02	+40 B +13 B