feat(render): indoor render WORKS — terminating portal flood + every-cell seal + look-in FPS

Checkpoint of the unified retail-faithful indoor render. The two-week HANG/grey is fixed and the
interior seals (live-verified by the user). Commits the session render-rewrite foundation together
with the fixes that made it functional.

- HANG fix: PortalVisibilityBuilder.Build portal flood did not terminate (the faithful ProjectToClip
  near-side clip drifts per round, defeating the CellView dedup; the BFS had no bound after U.2a removed
  MaxReprocessPerCell). Fix = drift-tolerant snapped/canonical CellView.Add dedup (PortalView.cs) plus
  restored MaxReprocessPerCell=16 bounded re-enqueue (PortalVisibilityBuilder.cs). Re-enqueue is kept
  (load-bearing for late-slice propagation, Build_ViewGrowthAfterDoneCell_PropagatesNewSlicesToExit);
  only its count is capped. CellViewDedupTests added.
- Seal (DrawCells Task 2): RetailPViewRenderer.DrawEnvCellShells draws EVERY visible cell via
  IndoorDrawPlan.ShellPass (was gated on the ClipFrameAssembler slot filter, leaving slot-less cells grey).
- Look-in FPS: GameWindow exterior look-in candidates limited to the player landblock +-1 (was all ~81
  loaded LBs iterated every outdoor frame). No behaviour change (far cells were >48m, already culled).

Remaining dominant issue = the FLAP at transitions: viewer-cell metastability (render roots at the
camera-eye cell, which oscillates outdoor-indoor as the 3rd-person boom drifts across the doorway,
confirmed in render-sig). SEPARATE fix, NOT the DrawCells port. Full handoff + flap fix plan + tracked
follow-ups (#78 terrain, look-in-from-inside, look-in FPS, L-spotlight):
docs/research/2026-06-07-indoor-render-session-handoff.md.

Baselines: build 0 err; App.Tests 210/210; Core.Tests 1331 pass / 4 fail (pre-existing) / 1 skip.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs

@@ -144,8 +144,8 @@ public sealed unsafe class WbDrawDispatcher : IDisposable
     // each Draw. When _clipRoutingActive is false (the U.3 path / outdoor root /
     // no portal frame), every instance maps to slot 0 (no-clip) and no instance is
     // culled — identical to U.3. When active, each instance's slot is resolved by
-    // ResolveEntitySlot per the U.4 policy (live-dynamic unclipped; cell statics to
-    // their cell slot; outdoor scenery to the OutsideView slot; non-visible culled).
+    // ResolveEntitySlot per the U.4 policy (cell-owned entities to their cell slot;
+    // outdoor-owned entities to OutsideView; non-visible/unresolved indoors culled).
     private bool _clipRoutingActive;
     private IReadOnlyDictionary<uint, int>? _cellIdToSlot;
     private int _outdoorSlot;
@@ -310,8 +310,8 @@ public sealed unsafe class WbDrawDispatcher : IDisposable
     /// Phase U.4: install the per-frame clip-slot routing for an INDOOR root.
     /// Call once per frame BEFORE <see cref="Draw"/> when the camera's root cell is
     /// non-null; the next <see cref="Draw"/> resolves each instance's binding=3
-    /// clip slot via the U.4 policy (live-dynamic unclipped, cell statics to their
-    /// cell slot, outdoor scenery to the OutsideView slot, non-visible culled).
+    /// clip slot via the U.4 policy (cell-owned entities to their cell slot,
+    /// outdoor-owned entities to OutsideView, non-visible/unresolved indoors culled).
     /// Pair with <see cref="ClearClipRouting"/> on outdoor-root frames so the
     /// dispatcher reverts to the U.3 no-clip-everything behavior.
     /// </summary>
@@ -354,12 +354,10 @@ public sealed unsafe class WbDrawDispatcher : IDisposable
     /// Phase U.4: resolve the clip slot for one entity per the slot/gate policy.
     /// Returns <see cref="ClipSlotCull"/> to drop the entity's instances entirely.
     /// <list type="bullet">
-    /// <item>ServerGuid != 0 (live dynamic: player / NPC / items / doors) ⇒ slot 0
-    /// (UNCLIPPED — retail draws live-dynamic unclipped; depth only).</item>
-    /// <item>ParentCellId != null (cell static) ⇒ the cell's slot, or CULL when the
-    /// cell isn't in <paramref name="cellIdToSlot"/> (not visible / nothing-visible).</item>
-    /// <item>ParentCellId == null (outdoor scenery / building shell) ⇒ the OutsideView
-    /// slot when <paramref name="outdoorVisible"/>, else CULL.</item>
+    /// <item>Indoor ParentCellId: the cell's slot, or CULL when hidden.</item>
+    /// <item>Outdoor ParentCellId or ParentCellId == null static scenery: the OutsideView slot
+    /// when <paramref name="outdoorVisible"/>, else CULL.</item>
+    /// <item>ServerGuid != 0 with ParentCellId == null: CULL while routing is active.</item>
     /// </list>
     /// Only called when <c>_clipRoutingActive</c> (indoor root). On the U.3 / outdoor
     /// path every instance is slot 0 and nothing is culled — see
@@ -385,20 +383,37 @@ public sealed unsafe class WbDrawDispatcher : IDisposable
         int outdoorSlot,
         bool outdoorVisible)
     {
-        // Live-dynamic entities render unclipped regardless of cell — retail draws
-        // the player / NPCs / dropped items through the depth buffer without portal
-        // clipping. ServerGuid is the live-dynamic marker (0 for dat-hydrated).
-        if (serverGuid != 0)
-            return 0;
-
+        // Live-dynamic entities are not a global indoor overlay. When they
+        // have current cell ownership, route them through the same visible
+        // cell/OutsideView graph as every other object. Parentless live objects
+        // are unresolved indoors, so cull them while clip routing is active.
         if (parentCellId is uint parentCell)
-            return cellIdToSlot.TryGetValue(parentCell, out int slot) ? slot : ClipSlotCull;
+        {
+            if (IsIndoorCellId(parentCell))
+            {
+                if (!cellIdToSlot.ContainsKey(parentCell))
+                    return ClipSlotCull;
+
+                return cellIdToSlot[parentCell];
+            }
+
+            return outdoorVisible ? outdoorSlot : ClipSlotCull;
+        }
+
+        if (serverGuid != 0)
+            return ClipSlotCull;
 
         // Outdoor scenery / building shell (no ParentCellId). Indoor root: gate to
         // the OutsideView slot, or cull when nothing outdoors is visible.
         return outdoorVisible ? outdoorSlot : ClipSlotCull;
     }
 
+    private static bool IsIndoorCellId(uint cellId)
+    {
+        uint low = cellId & 0xFFFFu;
+        return low >= 0x0100u && low != 0xFFFFu;
+    }
+
     /// <summary>
     /// Phase U.4: the call-site clip-slot decision for one entity, returning the
     /// <c>(Slot, Culled)</c> pair the per-entity loop body consumes. Wraps