- ue_import_site.py: auto_generate_collision=True so FBX static meshes get
real collision geometry (they imported with none -> complex-as-simple had
nothing to use, player fell through).
- ue_build_demo_map.py: PlayerStart cap raised to Z300 so the capsule feet
start above the ~Z99-138 terrain surface there (an embedded spawn point is
rejected -> 'NO PLAYERSTART with positive rating' -> origin fallback).
- Re-imported site meshes + rebuilt DemoMap with the above.
KNOWN-UNRESOLVED: packaged plain launch still spawns the capsule around
Z-123 and falls; downward trace finds no geometry. Map assets are all present
in the pak and referenced; runtime collision behavior needs a visual/interactive
check (headless commandlet traces are unreliable). Investigate on this branch;
do not merge to main.