fix(ui): bind radar to streamed world state

Resolve the live-entity spatial broadphase at snapshot time so retained UI construction cannot capture GameWindow's empty bootstrap GpuWorldState. Add a replacement-owner regression test covering the exact compass-without-blips failure.

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

src/AcDream.App/World/ILiveEntitySpatialQuery.cs

@@ -0,0 +1,16 @@
+using AcDream.Core.World;
+
+namespace AcDream.App.World;
+
+/// <summary>
+/// Read-only spatial broadphase for live server-object projections.
+/// Consumers resolve this owner late because <c>GameWindow</c> replaces its
+/// empty bootstrap world state after retained UI construction.
+/// </summary>
+public interface ILiveEntitySpatialQuery
+{
+    void CopyLiveEntitiesNearLandblock(
+        uint centerCellOrLandblockId,
+        int landblockRadius,
+        List<KeyValuePair<uint, WorldEntity>> destination);
+}