Flowers stand as 1px animated cutouts on their own pulled mesh (own-cell
flowers hide behind the walker, the cell south still overdraws feet).
Cuttable bushes, gym statues (single-block plinth) and Lt. Surge's trash
cans stand as 5-voxel prop cutouts; prop_ground names the tile painted
beneath. Block edits refresh meshes in place instead of blinking to 2D.