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/EntityClassificationCache.cs

@@ -76,13 +76,18 @@ internal sealed class EntityClassificationCache
     /// <c>(<paramref name="entityId"/>, <paramref name="landblockHint"/>)</c>
     /// tuple. Defensive: if an entry already exists, replaces it.
     /// </summary>
-    public void Populate(uint entityId, uint landblockHint, CachedBatch[] batches)
+    public void Populate(
+        uint entityId,
+        uint landblockHint,
+        CachedBatch[] batches,
+        CachedSelectionPart[]? selectionParts = null)
     {
         _entries[(entityId, landblockHint)] = new EntityCacheEntry
         {
             EntityId = entityId,
             LandblockHint = landblockHint,
             Batches = batches,
+            SelectionParts = selectionParts ?? [],
         };
     }