T6 (BR-7) C3: per-cell shadow architecture - flood registration, building channel, per-cell query; b3ce505 stopgap DELETED (closes #99)

The A6.P4 port, fused into one installment per the BR-2 half-port lesson
(registration and query are co-dependent: flood-registering shells under
the old radial query would re-open #98 through the vestibule).

REGISTRATION (ShadowObjectRegistry rewritten):
- Register/RegisterMultiPart/UpdatePosition compute the cell set via
  CellTransit.BuildShadowCellSet (the C2 find_cell_list flood) seeded by
  the entity's m_position cell id; the private 24m XY-grid rectangle and
  its single-landblock clamp are deleted. Flood spheres follow retail's
  CylSphere rule (base point + cyl radius, cap 10; BSP bounding-sphere
  fallback - Ghidra 0x0052b9f0). Statics flood with the do_not_load
  prune; dynamics (server spawns, isStatic:false) without.
- Keep-when-empty (SetPositionInternal num_cells gate, pc:283540): a
  failed flood leaves the previous registration in place.
- RefloodLandblock: streaming-race hook re-runs the flood when a
  landblock's cells hydrate (retail init_objects -> recalc_cross_cells,
  Ghidra 0x0052b420/0x00515a30); wired at GameWindow's hydration tail.
- GameWindow sites pass the server position's full cell id as the seed
  (spawn + UpdatePosition); the five static sites pass ParentCellId.

BUILDING CHANNEL (CSortCell.building shape):
- Building SHELLS are not shadow objects in retail (only caller of
  find_building_collisions is CSortCell::find_collisions 0x005340aa;
  one building per origin landcell, init_buildings 0x0052fd80 verified
  verbatim + ACE cross-ref). IsBuildingShell entities skip the registry;
  Transition.FindBuildingCollisions runs the shell part-0 BSP off
  cache.GetBuilding(cellId) with bldg_check set around it
  (find_building_collisions 0x006b5300), CollidedWithEnvironment on
  non-Contact non-OK. BuildingPhysics.ModelId = pre-resolved part-0
  GfxObj (0x02 Setups resolved at the CacheBuilding site).
- Placement/ethereal weakening: BSPQuery Path 1 passes center_solid=0
  when BldgCheck && HitsInteriorCell (BSPTREE::find_collisions 0x0053a82e
  + placement_insert 0x005399d8) so doorway crossings don't hard-fail
  against shell solids. SpherePath gains both retail fields;
  HitsInteriorCell is rebuilt at every cell-array build
  (build_cell_array reset 0x00509ef2 + find_cell_list/check_building_
  transit set sites).

QUERY (retail per-cell order, transitional_insert 0x0050b6f0):
- TransitionalInsert per attempt: env -> building (LandCell only) ->
  objects on the PRIMARY cell, then on OK the check_other_cells pass
  (env -> building -> objects per OTHER overlapped cell) + the
  carried-cell advance - the advance now happens AFTER all per-cell
  object passes (the WF1 ordering divergence), with Adjusted/Slid
  feeding the retry exactly like retail's OK_TS case.
- FindObjCollisionsInCell = CObjCell::find_obj_collisions (0x0052b750):
  iterate ONLY the asked cell's list. DELETED: the radial 9-landblock
  sweep, the +5m query pad, the b3ce505 indoor-primary gate, and the
  isViewer exemption (the camera is bounded by interior cell-BSP env
  collision - retail's own channel; CameraCornerSealReplayTests pins it
  against real dat, and the new building-channel camera test pins the
  outdoor stop).

TESTS: Core 1416/0/2 (was 1398 + 4 pre-existing #99-era fails + 1 skip),
App 225, UI 420, Net 294 - all green.
- 3 of the 4 #99-era reds flipped green as designed: the door apparatus
  (Apparatus_Grounded_50cmOffCenter_FrontApproach_Blocks) and tick-13558
  (indoor walkthrough) now assert the door BLOCKS; tick-22760 pins the
  outdoor blocking invariant.
- The 4th (BSPStepUp D4) + 22760's lateral-slide delta are NOT cell-set
  problems (probes prove the door is found + BSP-only dispatched;
  BR-7 left both byte-identical) - filed as issue #116 (slide-response
  family), D4 skipped with the issue reference.
- FindEnvCollisionsMultiCellTests migrated to the public entry (the A4
  multi-cell halt now lives at the retail call site).
- New registry pins: per-cell query surface, outdoor-footprint-never-
  indoor (#98 architectural), door-outdoor-cell membership, reflood.
- CameraCollisionIndoorTests rewritten against the building channel
  (the isViewer-exemption pins died with the exemption).

Closes #99 (doors block both ways via registration-time cell membership
+ the straddle-spanning player cell array). #97 likely closed (the +5m
radial pad that produced phantom-collision candidates is gone) - verify
at T5. #98 stays closed ARCHITECTURALLY (outdoor footprints structurally
cannot reach interior cells; the cellar harness stays green).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/AcDream.Core.Tests/Physics/CellarUpTrajectoryReplayTests.cs

@@ -1177,11 +1177,13 @@ public class CellarUpTrajectoryReplayTests : IDisposable
             landblockId:   0xA9B40000u,
             collisionType: ShadowCollisionType.BSP,
             scale:         1.0f,
-            // Landblock-baked statics in production (GameWindow.cs:5899) use
-            // `entity.ParentCellId ?? 0u` — the cottage building has no
-            // ParentCellId (it's a top-level landblock static), so the
-            // scope is landblock-wide (cellScope=0).
-            cellScope:     0u);
+            // BR-7: outdoor seed derived from the world position. (In
+            // production the cottage SHELL no longer registers as a shadow
+            // object at all — it dispatches via the per-LandCell building
+            // channel; this fixture keeps the shadow registration to pin the
+            // #98 regression shape: an outdoor-registered footprint must
+            // stay invisible to fully-interior cellar queries.)
+            seedCellId:    0u);
     }
 
     /// <summary>