fix: support WebP glTF mesh nodes

[DrHepa]

Summary

• Register glTF Transform extensions when mesh workflow nodes read GLB files.
• Add @gltf-transform/extensions to mesh-optimizer and mesh-exporter node dependencies.
• Fixes Pixal3D GLBs that require EXT_texture_webp failing in Optimize Mesh / Mesh Exporter.

Context

Pixal3D exports textured GLBs with EXT_texture_webp marked as required. Blender can open these files, but Modly mesh workflow nodes used bare NodeIO instances and failed with:

Missing required extension, "EXT_texture_webp"

Changes

File	Change
src/areas/workflows/nodes/mesh-optimizer/processor.ts	Register ALL_EXTENSIONS on NodeIO.
src/areas/workflows/nodes/mesh-optimizer/package.json	Add @gltf-transform/extensions dependency.
src/areas/workflows/nodes/mesh-exporter/processor.ts	Register ALL_EXTENSIONS on NodeIO.
src/areas/workflows/nodes/mesh-exporter/package.json	Add @gltf-transform/extensions dependency.

Test Plan

• Ran focused Node test before removing temporary test scaffolding: node --test --experimental-strip-types --experimental-loader ./scripts/node-ts-extensionless-loader.mjs src/areas/workflows/nodes/gltf-extension-registration.test.ts
• Ran git diff --check
• Full build not run.