Cache GLTF model loads

[JacKane21]

Closes #93

/claim #93

Changes

• Adds a shared GLTF/GLB scene cache keyed by normalized model URL, matching the existing OBJ-path idea so repeated models do not refetch/reparse.
• Clones cached scenes per rendered instance and clones mesh materials so hover/translucency/env-map mutations do not leak across repeated parts.
• Splits GLTF loading from isTranslucent updates, so translucency changes update materials on the loaded scene without triggering a fresh model load.
• Disposes cloned instance materials when a model is replaced, unmounted, or finishes loading after cancellation.

Validation

• ./node_modules/.bin/biome check src/three-components/GltfModel.tsx src/utils/gltf-model-cache.ts tests/gltf-model-cache.test.ts
• npx --yes tsc --noEmit --pretty false
• npx --yes bun test tests/gltf-model-cache.test.ts tests/cad-model-transform.test.ts tests/cad-model-fit.test.ts -> 17 passed
• npm run build
• git diff --check

Note: the local shell does not have a global bun, so I used npx --yes bun for the focused Bun tests and npm-installed tooling for build/type/format verification.

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Project	Deployment	Actions	Updated (UTC)
3d-viewer	Ready	Preview, Comment	May 22, 2026 6:02pm

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Clone GLTF scenes with SkeletonUtils

Replace scene.clone(true) here with SkeletonUtils.clone(...) for cached instance creation. Object3D.clone does not reliably preserve bone associations for SkinnedMesh hierarchies, so rigs/animations can break or share incorrect skeleton state when the loaded GLTF contains skinned content. This only appears for GLTF assets that include skinning, but in that case repeated cached instances may render or animate incorrectly.

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[JacKane21]

Closing this out as part of wrapping up my bounty/OSS cleanup. Thanks for the time and review.