Port retail CObjCell::find_cell_list do_not_load_cells prune
(acclient_2013_pseudo_c.txt:308829-308867) as indoor->outdoor doorway
hysteresis: hold the previous indoor cell when the outdoor candidate is
not in its stab list AND the foot-sphere still overlaps the cell's
containment BSP expanded by DoorwayHoldMargin. Kills the front-door
0170<->0031 ping-pong (handoff §5) the #98 saga never addressed. Fires
only at the front-door seam; the cellar has no exit portal so it never
falls through here (#98 cellar-up untouched).
Three TDD tests in CellGraphMembershipTests: HOLD (the RED->GREEN case,
Y=3.9 inside the 0.2 m margin), RELEASE when fully outside (Y=4.5
exceeds expanded margin), and stab-list gate (outdoor candidate in stab
list releases even near the boundary).
Adds using System.Linq for IReadOnlyList.Contains at the prune site.
SphereOverlapsEnvCell helper mirrors BSPQuery.SphereIntersectsCellBsp
via EnvCell.InverseWorldTransform + ContainmentBsp.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>