fix(rendering): port retail shared alpha list

Queue translucent world GfxObj batches and scene particles in one stable far-to-near stream using transformed DAT sort centers, then drain it at retail's landscape and final-world boundaries. Preserve authored blend, cull, lighting, opacity, and adjacent-only batching so particles behind lifestones are composited through the crystal instead of overpainting it.

Release build succeeds and all 5,914 tests pass with five intentional skips.

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

tests/AcDream.App.Tests/Rendering/RetailAlphaQueueTests.cs

@@ -0,0 +1,128 @@
+using System.Numerics;
+using AcDream.App.Rendering;
+
+namespace AcDream.App.Tests.Rendering;
+
+public sealed class RetailAlphaQueueTests
+{
+    [Fact]
+    public void Flush_InterleavesRenderersInDescendingCyptOrder()
+    {
+        var log = new List<string>();
+        var objects = new RecordingSource("object", log);
+        var particles = new RecordingSource("particle", log);
+        var queue = new RetailAlphaQueue();
+
+        queue.BeginFrame();
+        queue.Submit(objects, token: 0, viewerDistance: 10f);    // near crystal
+        queue.Submit(particles, token: 0, viewerDistance: 30f);  // far smoke
+        queue.Submit(objects, token: 1, viewerDistance: 25f);
+        queue.Submit(particles, token: 1, viewerDistance: 20f);
+        queue.Submit(objects, token: 2, viewerDistance: 5f);
+        queue.EndFrame();
+
+        Assert.Equal(
+            new[]
+            {
+                "particle:0",
+                "object:1",
+                "particle:1",
+                "object:0",
+                "object:2",
+            },
+            log);
+        Assert.Equal(1, objects.ResetCount);
+        Assert.Equal(1, particles.ResetCount);
+    }
+
+    [Fact]
+    public void Flush_EqualDistancePreservesSubmissionOrderAcrossRenderers()
+    {
+        var log = new List<string>();
+        var objects = new RecordingSource("object", log);
+        var particles = new RecordingSource("particle", log);
+        var queue = new RetailAlphaQueue();
+
+        queue.BeginFrame();
+        queue.Submit(objects, 7, 12f);
+        queue.Submit(particles, 4, 12f);
+        queue.Submit(objects, 8, 12f);
+        queue.EndFrame();
+
+        Assert.Equal(new[] { "object:7", "particle:4", "object:8" }, log);
+    }
+
+    [Fact]
+    public void Flush_KeepsFrameOpenForPostDepthClearScope()
+    {
+        var log = new List<string>();
+        var source = new RecordingSource("alpha", log);
+        var queue = new RetailAlphaQueue();
+
+        queue.BeginFrame();
+        queue.Submit(source, 1, 8f);
+        queue.Flush();
+
+        Assert.True(queue.IsCollecting);
+        Assert.Equal(0, queue.PendingCount);
+        queue.Submit(source, 2, 3f);
+        queue.EndFrame();
+
+        Assert.False(queue.IsCollecting);
+        Assert.Equal(new[] { "alpha:1", "alpha:2" }, log);
+        Assert.Equal(2, source.ResetCount);
+    }
+
+    [Fact]
+    public void Flush_BatchesOnlyAdjacentEntriesFromSameRenderer()
+    {
+        var log = new List<string>();
+        var objects = new RecordingSource("object", log);
+        var particles = new RecordingSource("particle", log);
+        var queue = new RetailAlphaQueue();
+
+        queue.BeginFrame();
+        queue.Submit(objects, 0, 40f);
+        queue.Submit(objects, 1, 35f);
+        queue.Submit(particles, 0, 30f);
+        queue.Submit(objects, 2, 25f);
+        queue.EndFrame();
+
+        Assert.Equal(new[] { 2, 1 }, objects.BatchSizes);
+        Assert.Equal(new[] { 1 }, particles.BatchSizes);
+    }
+
+    [Fact]
+    public void ComputeViewerDistance_UsesTransformedGfxSortCenter()
+    {
+        // Retail CPhysicsPart::UpdateViewerDistance 0x0050E030 applies scale,
+        // orientation, and translation to gfxobj.sort_center before CYpt.
+        var model = Matrix4x4.CreateScale(2f)
+                    * Matrix4x4.CreateRotationZ(MathF.PI / 2f)
+                    * Matrix4x4.CreateTranslation(10f, 20f, 30f);
+        Vector3 localSortCenter = new(1f, 0f, 0f);
+        Vector3 camera = new(10f, 20f, 30f);
+
+        float cypt = RetailAlphaOrdering.ComputeViewerDistance(
+            localSortCenter,
+            model,
+            camera);
+
+        Assert.Equal(2f, cypt, precision: 5);
+    }
+
+    private sealed class RecordingSource(string name, List<string> log) : IRetailAlphaDrawSource
+    {
+        public List<int> BatchSizes { get; } = new();
+        public int ResetCount { get; private set; }
+
+        public void DrawAlphaBatch(ReadOnlySpan<int> tokens)
+        {
+            BatchSizes.Add(tokens.Length);
+            foreach (int token in tokens)
+                log.Add($"{name}:{token}");
+        }
+
+        public void ResetAlphaSubmissions() => ResetCount++;
+    }
+}