fix #225: stabilize render pacing and frame CPU

Replace scheduler-quantized software sleeps with a reusable Windows high-resolution deadline timer, expose pacing in the frame profiler, and make shutdown wake every persistent mesh worker without losing the shared signal.

Preserve retail alpha order while using a stable radix, skip duplicate deferred-alpha SSBO packing, pack light sets, cache static selection descriptors, and retire historical material groups at the whole-frame boundary. The fixed dense-Caul sample improved from roughly 9-12 ms CPU to 5.3-6.2 ms without reducing visual quality.

Release build succeeds with zero warnings and all 6,300 tests pass with five intentional skips. Three independent retail, architecture, and adversarial reviews are clean; the post-review connected route remains pending because local ACE is offline.

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

src/AcDream.App/Rendering/Wb/CachedBatch.cs

@@ -10,6 +10,9 @@ namespace AcDream.App.Rendering.Wb;
 /// <c>subPart.PartTransform * meshRef.PartTransform</c> product.
 /// <see cref="LocalSortCenter"/> preserves the authored GfxObj key used by
 /// retail's delayed-alpha viewer-distance ordering on cache hits.
+/// <see cref="Group"/> is a registration-checked fast handle into the
+/// dispatcher's bounded group table; a retired or synthetic entry falls back
+/// to key lookup and refreshes this array entry.
 ///
 /// Accessibility: <c>internal</c> because <see cref="GroupKey"/> is
 /// <c>internal</c> and shows up in this struct's constructor / <c>Deconstruct</c>
@@ -21,7 +24,19 @@ internal readonly record struct CachedBatch(
     GroupKey Key,
     ulong BindlessTextureHandle,
     Matrix4x4 RestPose,
-    Vector3 LocalSortCenter = default);
+    Vector3 LocalSortCenter = default,
+    WbDrawDispatcher.InstanceGroup? Group = null,
+    long GroupRegistration = 0);
+
+/// <summary>
+/// Immutable retail-picking descriptor for one static entity part. The cache
+/// stores only authored identity and rest pose; the current entity transform
+/// and the selection system's live frustum/geometry verdict remain per-frame.
+/// </summary>
+internal readonly record struct CachedSelectionPart(
+    int PartIndex,
+    uint GfxObjId,
+    Matrix4x4 RestPose);
 
 /// <summary>
 /// One entity's cached classification. <see cref="Batches"/> is flat across
@@ -39,4 +54,5 @@ internal sealed class EntityCacheEntry
     public required uint EntityId { get; init; }
     public required uint LandblockHint { get; init; }
     public required CachedBatch[] Batches { get; init; }
+    public CachedSelectionPart[] SelectionParts { get; init; } = [];
 }