WalkWorldDatAdapter builds WalkCell/WalkBuilding from real DATs: cell
portals with the PortalSide flag bit and signed OtherPortalId, portal
polygons + planes via the production formula, stab lists, building
position cells (24 m landcell math), building portals with stab lists,
and the drawing-BSP -> WalkBspNode conversion incl. PORT-node PortalRef
polygons (the previously missing consumers the 2026-08-30 survey named).
Lane=InstalledDat conformance: every BLD id the FW0 oracle traces saw
retail draw (26 buildings over 7 landblocks) resolves in the adapter
roster at its EXACT position cell; the traced look-in cells build with
portals/polygons/stabs; the sanctuary BSP carries portal refs. 9/9.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
