feat(rendering): pack scene dispatcher inputs

Capture immutable presentation payloads in the render scene, flatten unique entity and mesh-part records into the borrowed frame arena, and compare every routed dispatcher input tuple without changing the production draw source.

tests/AcDream.App.Tests/Rendering/CurrentRenderSceneOracleTests.cs

@@ -406,6 +406,41 @@ public sealed class CurrentRenderSceneOracleTests
         }
     }
 
+    [Fact]
+    public void SurfaceOverrideFingerprint_IsOrderIndependentAndContentExact()
+    {
+        var first = new Dictionary<uint, uint>
+        {
+            [0x0800_0002] = 0x0500_0012,
+            [0x0800_0001] = 0x0500_0011,
+        };
+        var reordered = new Dictionary<uint, uint>
+        {
+            [0x0800_0001] = 0x0500_0011,
+            [0x0800_0002] = 0x0500_0012,
+        };
+        var changed = new Dictionary<uint, uint>
+        {
+            [0x0800_0001] = 0x0500_0011,
+            [0x0800_0002] = 0x0500_0013,
+        };
+
+        RenderSceneHash128 expected =
+            CurrentRenderSceneOracle.CreateSurfaceOverrideFingerprint(first);
+
+        Assert.Equal(
+            expected,
+            CurrentRenderSceneOracle.CreateSurfaceOverrideFingerprint(
+                reordered));
+        Assert.NotEqual(
+            expected,
+            CurrentRenderSceneOracle.CreateSurfaceOverrideFingerprint(
+                changed));
+        Assert.NotEqual(
+            expected,
+            CurrentRenderSceneOracle.CreateSurfaceOverrideFingerprint(null));
+    }
+
     private static CurrentRenderProjectionFingerprint CaptureSingle(
         WorldEntity entity,
         uint landblockId,