fix(rendering): preserve exact scene traversal order

src/AcDream.App/Rendering/Scene/GpuWorldRenderTraversalOrderSource.cs

@@ -0,0 +1,21 @@
+using AcDream.App.Streaming;
+using AcDream.Core.World;
+
+namespace AcDream.App.Rendering.Scene;
+
+/// <summary>
+/// Narrow derived adapter over <see cref="GpuWorldState"/>'s canonical spatial
+/// traversal. It exposes no bucket mutation or gameplay lookup to the render
+/// scene.
+/// </summary>
+internal sealed class GpuWorldRenderTraversalOrderSource(
+    GpuWorldState world) : IRenderTraversalOrderSource
+{
+    private readonly GpuWorldState _world =
+        world ?? throw new ArgumentNullException(nameof(world));
+
+    public bool TryGetTraversalSortKey(
+        WorldEntity entity,
+        out RenderSortKey sortKey) =>
+        _world.TryGetRenderTraversalSortKey(entity, out sortKey);
+}