[codex] Cache direct STL URL geometry loads

[newmattock]

/claim #93

Summary

• add a shared cache helper for direct STL URL geometry loads, keyed by a normalized URL that strips only cachebust_origin
• return a cloned BufferGeometry per caller so component cleanup cannot dispose the cached template
• wire the STLModel stlUrl path through the cache while leaving direct stlData parsing unchanged
• clean touched-file Biome issues in STLModel

Non-overlap

The active PRs I found cover OBJ loader cache keys, GLTF/GLB loader caching, generic load3DModel URL detection, and the STEP-to-GLB path. This PR only touches the direct STLModel stlUrl geometry loading path.

Verification

• bun test tests/load-cached-stl-geometry.test.ts
• bunx tsc --noEmit
• bunx biome check src/three-components/STLModel.tsx src/utils/load-cached-stl-geometry.ts tests/load-cached-stl-geometry.test.ts
• git diff --check
• bun run build
• GitHub checks are green: format-check, Test Node Bundle Load, type-check, Vercel, and Vercel Preview Comments

AI-assisted with Codex; I reviewed the diff before submitting.

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Project	Deployment	Actions	Updated (UTC)
3d-viewer	Ready	Preview, Comment	May 12, 2026 10:25pm