#1467 (preserve): recursively removes a structural construction child that has
no valid foundation to live on, preserving any loot nested inside it as
world-owned (persisted) construction first. Used by the no-surviving-parent
("whole deck removed" / broken parent chain) paths so player loot is never
silently lost while the structural pieces are cleaned up. Never touches
_worldSimpleConstruction (that holds regenerated, non-persisted world props),
and despawns each removed structure via deleteEntity.
#1467 (preserve): recursively removes a structural construction child that has no valid foundation to live on, preserving any loot nested inside it as world-owned (persisted) construction first. Used by the no-surviving-parent ("whole deck removed" / broken parent chain) paths so player loot is never silently lost while the structural pieces are cleaned up. Never touches _worldSimpleConstruction (that holds regenerated, non-persisted world props), and despawns each removed structure via deleteEntity.