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/Streaming/WorldGenerationQuiescenceTests.cs

@@ -0,0 +1,123 @@
+using System.Numerics;
+using AcDream.App.Audio;
+using AcDream.App.Streaming;
+using AcDream.Core.Selection;
+using AcDream.Core.World;
+using DatReaderWriter.DBObjs;
+
+namespace AcDream.App.Tests.Streaming;
+
+public sealed class WorldGenerationQuiescenceTests
+{
+    private const uint LandblockId = 0x1010FFFFu;
+    private const uint ServerGuid = 0x70000001u;
+
+    [Fact]
+    public void ActiveGeneration_HidesWorldQueriesButRetainsCanonicalOwners()
+    {
+        var availability = new WorldGenerationAvailabilityState();
+        var world = new GpuWorldState(availability: availability);
+        WorldEntity entity = Entity();
+        world.AddLandblock(new LoadedLandblock(
+            LandblockId,
+            new LandBlock(),
+            Array.Empty<WorldEntity>()));
+        world.PlaceLiveEntityProjection(LandblockId, entity);
+        world.SetLandblockAabb(LandblockId, Vector3.Zero, Vector3.One);
+        var nearby = new List<KeyValuePair<uint, WorldEntity>>();
+
+        Assert.True(world.IsLiveEntityVisible(ServerGuid));
+        Assert.Single(world.LandblockEntries);
+        Assert.Single(world.LandblockBounds);
+
+        availability.Begin(17);
+        world.CopyLiveEntitiesNearLandblock(LandblockId, 0, nearby);
+
+        Assert.False(availability.IsWorldAvailable);
+        Assert.False(world.IsLiveEntityVisible(ServerGuid));
+        Assert.Empty(world.LandblockEntries);
+        Assert.Empty(world.LandblockBounds);
+        Assert.Empty(nearby);
+        Assert.Same(entity, Assert.Single(world.Entities));
+        Assert.True(world.IsLoaded(LandblockId));
+
+        Assert.False(availability.End(16));
+        Assert.False(availability.IsWorldAvailable);
+        Assert.True(availability.End(17));
+        Assert.True(world.IsLiveEntityVisible(ServerGuid));
+        Assert.Same(entity, Assert.Single(world.LandblockEntries).Entities.Single());
+    }
+
+    [Fact]
+    public void SupersededReveal_StaysContinuouslySilentAndOnlyLatestGenerationReopens()
+    {
+        var availability = new WorldGenerationAvailabilityState();
+        var world = new GpuWorldState(availability: availability);
+        world.AddLandblock(new LoadedLandblock(
+            LandblockId,
+            new LandBlock(),
+            Array.Empty<WorldEntity>()));
+        world.PlaceLiveEntityProjection(LandblockId, Entity());
+        var selection = new SelectionState();
+        selection.Select(ServerGuid, SelectionChangeSource.World);
+        var audio = new RecordingAudioQuiescence();
+        var quiescence = new WorldGenerationQuiescence(
+            availability,
+            selection,
+            world,
+            audio);
+
+        quiescence.Begin(1);
+        quiescence.Begin(2);
+        quiescence.End(1);
+
+        Assert.False(availability.IsWorldAvailable);
+        Assert.Equal(2, availability.QuiescedGeneration);
+        Assert.Null(selection.SelectedObjectId);
+        Assert.Equal(1, audio.SuspendCalls);
+        Assert.Equal(0, audio.ResumeCalls);
+
+        quiescence.End(2);
+
+        Assert.True(availability.IsWorldAvailable);
+        Assert.Equal(1, audio.ResumeCalls);
+    }
+
+    [Fact]
+    public void Quiesce_PreservesNonWorldInventorySelection()
+    {
+        const uint inventoryGuid = 0x80000001u;
+        var availability = new WorldGenerationAvailabilityState();
+        var world = new GpuWorldState(availability: availability);
+        var selection = new SelectionState();
+        selection.Select(inventoryGuid, SelectionChangeSource.Inventory);
+        var quiescence = new WorldGenerationQuiescence(
+            availability,
+            selection,
+            world,
+            audio: null);
+
+        quiescence.Begin(3);
+
+        Assert.Equal(inventoryGuid, selection.SelectedObjectId);
+    }
+
+    private static WorldEntity Entity() => new()
+    {
+        Id = 1,
+        ServerGuid = ServerGuid,
+        SourceGfxObjOrSetupId = 0x02000001u,
+        Position = Vector3.Zero,
+        Rotation = Quaternion.Identity,
+        MeshRefs = Array.Empty<MeshRef>(),
+    };
+
+    private sealed class RecordingAudioQuiescence : IWorldAudioQuiescence
+    {
+        public int SuspendCalls { get; private set; }
+        public int ResumeCalls { get; private set; }
+
+        public void SuspendWorldAudio() => SuspendCalls++;
+        public void ResumeWorldAudio() => ResumeCalls++;
+    }
+}