Add OWL field widget (fp_3d_preview) that renders uploaded STL files
in an interactive 3D viewport:
- Three.js r170 ESM loaded lazily via dynamic import with importmap
- STLLoader + OrbitControls for full model interaction
- Fallback binary STL parser when addon import fails
- Toolbar with wireframe toggle and camera reset
- Vertex/face count display
- Theme-aware SCSS using CSS custom properties and $border-color
- Registered on model_attachment_id in the Part Catalog form
Vendored libs: three.module.min.js (691KB), STLLoader.js, OrbitControls.js
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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