Upstream: https://github.com/FGMEMBERS/E-jet-family/tree/45be9f83c479c5df6a03b117513aae740ffe9cc3
Corresponding editable AC3D and scene XML inputs retained unchanged.
Preparation: neutral surfaces; omit named running gear; triangulate polygons with source winding; crease-based normals; rigid transforms and source XML engine offsets; merge retained surfaces. See scripts/gear3d-body-assets/ac3d.js and the regional-hubs review.
