Fix jlcpcb CAD fallback for library footprints

[techmannih]

What changed

This updates CAD fallback generation for library-style footprints so cad_component.footprinter_string is only emitted for direct footprinter strings such as 0402 or soic8.

For library references like jlcpcb:C51950748, KiCad library refs, URLs, and static asset paths, the fallback now emits a bounding-box CAD component instead of forwarding the library reference as a footprinter string.

Why this changed

The 3D viewer was trying to parse jlcpcb:... as a raw footprinter function when no CAD model was available. That produced runtime errors like:

Invalid footprint function, got "jlcpcb"

The underlying footprint could still load for PCB rendering, but the CAD fallback path was sending an invalid string into the 3D engine.

Impact

This fixes 3D rendering for library footprints that do not provide a CAD model by falling back cleanly to a bounding box instead of surfacing a parser error.

Root cause

NormalComponent.doInitialCadModelRender() treated any string footprint as a valid footprinter_string fallback. Library refs such as jlcpcb:... are valid footprint lookup keys, but they are not valid raw footprinter expressions.

Validation

• bun test tests/footprint/footprint-library-map-jlcpcb-cadmodel.test.tsx
• bun test tests/components/normal-components/cad-component-bounding-box.test.tsx

Notes

Repo-wide build/type generation still has unrelated pre-existing DTS failures in lib/components/primitive-components/PcbTrace.ts.

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Project	Deployment	Actions	Updated (UTC)
tscircuit-core-benchmarks	Ready	Preview, Comment	May 17, 2026 7:47pm

[seveibar]

bad naming, the fix is valid but there are issues:

1. canUseFootprintStringFallback is unclear. There is no fallback. Better naming is needed e.g. footprintIsFootprinterString is more clear
2. Ternary usage is confusing
3. !! is never allowed