refactor(runtime): own canonical entity and object lifetime

Introduce one presentation-free RuntimeEntityObjectLifetime for the exact entity directory and ClientObjectTable. Make GameWindow, graphical projections, retained UI, interaction, session routing, create/delete integration, and reset borrow that owner while preserving synchronous retail ordering, dormant retention, and retry semantics.

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

tests/AcDream.App.Tests/LiveEntityRuntimeFixture.cs

@@ -0,0 +1,50 @@
+using AcDream.App.Streaming;
+using AcDream.App.World;
+using AcDream.Runtime.Entities;
+
+namespace AcDream.App.Tests;
+
+/// <summary>
+/// Explicit isolated lifetime-group seam for App projection tests. Production
+/// composition supplies its session-owned group from GameWindow; focused tests
+/// use a fresh group per runtime so identity never leaks between fixtures.
+/// </summary>
+internal static class LiveEntityRuntimeFixture
+{
+    public static LiveEntityRuntime Create(
+        GpuWorldState spatial,
+        ILiveEntityResourceLifecycle resources,
+        uint firstLocalEntityId = RuntimeEntityDirectory.FirstLocalEntityId)
+    {
+        var lifetime = new RuntimeEntityObjectLifetime(firstLocalEntityId);
+        return new LiveEntityRuntime(spatial, resources, lifetime);
+    }
+
+    public static LiveEntityRuntime Create(
+        GpuWorldState spatial,
+        ILiveEntityResourceLifecycle resources,
+        Action<LiveEntityRecord> tearDownRuntimeComponents,
+        uint firstLocalEntityId = RuntimeEntityDirectory.FirstLocalEntityId)
+    {
+        var lifetime = new RuntimeEntityObjectLifetime(firstLocalEntityId);
+        return new LiveEntityRuntime(
+            spatial,
+            resources,
+            tearDownRuntimeComponents,
+            lifetime);
+    }
+
+    public static LiveEntityRuntime Create(
+        GpuWorldState spatial,
+        ILiveEntityResourceLifecycle resources,
+        ILiveEntityRuntimeComponentLifecycle runtimeComponentLifecycle,
+        uint firstLocalEntityId = RuntimeEntityDirectory.FirstLocalEntityId)
+    {
+        var lifetime = new RuntimeEntityObjectLifetime(firstLocalEntityId);
+        return new LiveEntityRuntime(
+            spatial,
+            resources,
+            runtimeComponentLifecycle,
+            lifetime);
+    }
+}