perf(streaming): scope reveal warmup spatially

Source composite warmup from the canonical published destination neighborhood, including quiesced static and live projections, instead of rescanning the retained Far-tier world after every membership edge.

This lifecycle correction applies to both draw paths, preserving ef1d263337 as the sole G4 visual rollback.

Co-authored-by: OpenAI Codex <codex@openai.com>

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

@@ -0,0 +1,59 @@
+using AcDream.App.Streaming;
+using AcDream.Core.World;
+
+namespace AcDream.App.Rendering.Wb;
+
+/// <summary>
+/// Retains the exact published destination-neighborhood snapshot consumed by
+/// composite-texture reveal warmup. The source refreshes only when canonical
+/// spatial membership or its destination scope changes, avoiding a scan of
+/// the retained Far-tier world on every reveal tick.
+/// </summary>
+internal sealed class CompositeWarmupEntitySource
+{
+    private readonly GpuWorldState _world;
+    private readonly List<WorldEntity> _entities = [];
+    private bool _initialized;
+    private ulong _worldGeneration;
+    private uint _destinationCell;
+    private int _radius;
+
+    public CompositeWarmupEntitySource(GpuWorldState world)
+    {
+        _world = world ?? throw new ArgumentNullException(nameof(world));
+    }
+
+    public IReadOnlyList<WorldEntity> Entities => _entities;
+    public ulong Generation => _worldGeneration;
+
+    public void Refresh(uint destinationCell, int radius)
+    {
+        ArgumentOutOfRangeException.ThrowIfNegative(radius);
+        ulong worldGeneration = _world.FlatViewGeneration;
+        if (_initialized
+            && _worldGeneration == worldGeneration
+            && _destinationCell == destinationCell
+            && _radius == radius)
+        {
+            return;
+        }
+
+        _world.CopyPublishedEntitiesNearLandblockForReadiness(
+            destinationCell,
+            radius,
+            _entities);
+        _worldGeneration = worldGeneration;
+        _destinationCell = destinationCell;
+        _radius = radius;
+        _initialized = true;
+    }
+
+    public void Reset()
+    {
+        _entities.Clear();
+        _initialized = false;
+        _worldGeneration = 0;
+        _destinationCell = 0;
+        _radius = 0;
+    }
+}