fix(render): Phase A8 — animated entities exempt from stencil-gated outdoor pass

Visual verification of A8 (commit 41c2e67) surfaced a showstopper:
player + NPCs disappeared when the camera entered a building. Root
cause: live server-spawned entities (animated player/NPCs/monsters)
have ParentCellId == null. The EntitySet partition classified them
as "outdoor" and stencil-gated them in the OutdoorOnly pass — so
they only rendered where stencil bit 1 was set (portal silhouettes),
producing partial-body and head-backwards artifacts at doorway
transits and full invisibility everywhere else inside.

Fix: animatedEntityIds overrides the ParentCellId-based partition.
Animated entities always belong in the IndoorOnly pass (stencil OFF),
never in OutdoorOnly. Three changes:
- WalkEntitiesInto full-walk path: compute isAnimated up front, use
  it in both partition checks
- WalkEntitiesInto animated-only path: skip the entire path on
  OutdoorOnly (every iterated entity is animated by definition)
- WalkEntitiesForTest: add optional animatedEntityIds parameter,
  mirror the new partition logic

Two new tests cover:
- EntitySet_IndoorOnly_IncludesAnimatedEntitiesEvenWithNullParentCellId
- EntitySet_OutdoorOnly_ExcludesAnimatedEntities

Known remaining limitation: dropped items / static-but-live objects
have ParentCellId == null AND are NOT in animatedEntityIds, so they
still classify as outdoor scenery and stencil-gate. Addressing this
requires a "live entity" flag on WorldEntity — deferred.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/AcDream.Core.Tests/Rendering/Wb/WbDrawDispatcherEntitySetTests.cs

@@ -107,4 +107,69 @@ public class WbDrawDispatcherEntitySetTests
         Assert.Contains(0x10000002u, result);
         Assert.DoesNotContain(0x10000003u, result);
     }
+
+    // ---------------------------------------------------------------------
+    // Phase A8 fix (post-visual-verification): animated entities (player,
+    // NPCs, monsters) are live server-spawned objects with ParentCellId == null.
+    // Without these tests, they would be classified as outdoor scenery and
+    // stencil-gated by the OutdoorOnly pass — causing the character to
+    // disappear when the camera enters a building. Fix: animatedEntityIds
+    // overrides the ParentCellId-based partition. Animated entities always
+    // belong in the IndoorOnly pass, never in OutdoorOnly.
+    // ---------------------------------------------------------------------
+
+    [Fact]
+    public void EntitySet_IndoorOnly_IncludesAnimatedEntitiesEvenWithNullParentCellId()
+    {
+        var entities = new List<WorldEntity>
+        {
+            Indoor(0x10000001, 0xA9B40143),
+            Outdoor(0x10000002),                          // static outdoor scenery
+            Outdoor(0x40000005),                          // animated (player/NPC)
+        };
+
+        var visible = new HashSet<uint> { 0xA9B40143u };
+        var animated = new HashSet<uint> { 0x40000005u };
+
+        var result = WbDrawDispatcher.WalkEntitiesForTest(
+            entities,
+            visibleCellIds: visible,
+            set: WbDrawDispatcher.EntitySet.IndoorOnly,
+            animatedEntityIds: animated);
+
+        // Indoor entity passes via ParentCellId.HasValue.
+        // Outdoor scenery (0x10000002) fails — not animated, no ParentCellId.
+        // Animated entity (0x40000005) passes via animatedEntityIds override.
+        Assert.Equal(2, result.Count);
+        Assert.Contains(0x10000001u, result);
+        Assert.Contains(0x40000005u, result);
+        Assert.DoesNotContain(0x10000002u, result);
+    }
+
+    [Fact]
+    public void EntitySet_OutdoorOnly_ExcludesAnimatedEntities()
+    {
+        var entities = new List<WorldEntity>
+        {
+            Outdoor(0x10000002),                          // static outdoor scenery
+            Outdoor(0x40000005),                          // animated (player/NPC)
+            Outdoor(0x40000006),                          // animated (NPC)
+        };
+
+        var animated = new HashSet<uint> { 0x40000005u, 0x40000006u };
+
+        var result = WbDrawDispatcher.WalkEntitiesForTest(
+            entities,
+            visibleCellIds: null,
+            set: WbDrawDispatcher.EntitySet.OutdoorOnly,
+            animatedEntityIds: animated);
+
+        // Only static outdoor scenery passes the OutdoorOnly partition.
+        // Animated entities are explicitly excluded so they don't get
+        // stencil-gated (they're drawn in the IndoorOnly pass instead).
+        Assert.Single(result);
+        Assert.Contains(0x10000002u, result);
+        Assert.DoesNotContain(0x40000005u, result);
+        Assert.DoesNotContain(0x40000006u, result);
+    }
 }