The cone models recorded the old art's hash, so Corrode's cones did not
load with the 13.08 art. Rebuilt them changing only what 13.08 changed:

- walls: build_art.py on the 0497bec pieces outside the seven changed
  places plus the new art's ink; Riot's 13.08 vision lines inside those
  places, the 13.06 lines the shipped models used elsewhere
- standing: a ground patch from the 13.08 navmesh where the floor moved,
  stale supports cut, supports for the new boxes, barrels moved
- standable region rebuilt by standable_region.py
- navigation rebaked from the 13.08 Recast export; detailed floors kept
  for the polygons that did not change

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>