GET /api/ugc/assembly converts the UGC server's assembled .nif for the 3D
view. The icon parameter list names each parameter's group; the kinds carry a
sample (a model, or the most used combination) to edit a preset on. The icon
preview is viewable as the /ugc page. ugc-pose-math.js mirrors UgcIconPose and
both are checked against one fixture (gtest and node).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
