- Add build_preflight.sh to create obj/ dirs that git can't track (body/board/obj, panda/board/obj)
- Wire preflight into build_only.sh and launch_chffrplus.sh
- Restore missing third_party binaries (libyuv, snpe, acados, maplibre) that were text pointers
- Remove dead Qt5WebEngineWidgets dependency from UI SConscript
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
