Type guard: narrow attrs.transform from readonly number[] | undefined
to a Matrix4x4 16-tuple once the length-16 invariant has been
verified at runtime. The geometry-format check (column-major,
translation at indices [12,13,14]) is performed downstream by
validateTransformFormat in node-factory.ts.
Type guard: narrow
attrs.transformfromreadonly number[] | undefinedto a Matrix4x4 16-tuple once the length-16 invariant has been verified at runtime. The geometry-format check (column-major, translation at indices [12,13,14]) is performed downstream byvalidateTransformFormatinnode-factory.ts.