perf(streaming): quiesce retired generations and budget teardown

Publish the retail blocking-for-cells edge before deferred recenter work, freeze old-world presentation/simulation/audio, and advance full-window retirement from exact metered entity and owner cursors. This removes synchronous portal teardown without allowing retained owners to remain observable.

tests/AcDream.App.Tests/Net/LiveSessionResetPlanTests.cs

@@ -152,6 +152,13 @@ public sealed class LiveSessionResetPlanTests
         Assert.Equal(1, identityResets);
 
         failRetirement = false;
+        for (int frame = 0;
+             frame < 64
+             && !controller.IsOriginRecenterRetirementComplete();
+             frame++)
+        {
+            controller.Tick(0x53, 0x53);
+        }
         plan.Execute();
 
         Assert.Equal(2, identityResets);