measure(step2b): per-brick setup rebuilds the chunk caches -- 10x slower; live cost attributed

Editor-only brick API (<= 8^3 points per call, TunnelNetwork/Underwater op-stack routes, 1.16%
scalar fallback). Exact: 0 Q16/sign disagreements on the full 259^3 ring and the five-seed probe
set, same hash on 1 and 6 workers, reach shrink still caught (18,107 Q16 / 735 sign).
Speed: 69.19 s wall, 17.6 us/sample vs live 7.04 s, 1.65 us/sample. Stack sampler (inclusive):
BuildChunkCache 93.5%, PropagateSdfOverBox 92.5%, BuildActiveOpList 92.6% -- each brick rebuilds
the cache windows and active-op lists; EvalBlock itself is 3.6%.
Live path attribution (inclusive, 68,934 stacks): op-stack RoomGraph EvalBlock 54.4%, SDF and
spatial candidate scans ~28%, tunnel core 18.4%, passage floor segment 15.0%, structural posts
14.6%, noise octaves 2.6%, disturbances 0.6%, diff layer 0.3%.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MmSoF64BbRFmk9C3p1VsBJ

Source/VoxelForgeEditor/Private/VoxelForgeRegionEvalExperiment.h

@@ -17,10 +17,15 @@ namespace VoxelForgeRegionEval
         int32 Workers = WorkerCount;
         int32 ObservedWorkerThreads = 0;
         int64 SampleCount = 0;
+        int64 EvaluatedSamples = 0;
+        int64 BrickCount = 0;
+        int64 FallbackSamples = 0;
+        double FallbackShare = 0.0;
         double WallSeconds = 0.0;
         double WorkerCpuSeconds = 0.0;
         double NanosecondsPerSample = 0.0;
         bool bWorkerCpuFromOsThreadTimes = false;
+        bool bBrickProgram = false;
         uint64 QuantizedHash = 0;
         uint64 RawFloatHash = 0;
         uint64 SaturatedSamples = 0;
@@ -67,7 +72,9 @@ namespace VoxelForgeRegionEval
         bool bPrepared,
         float ReachScale,
         TArray<float>* OutDensities,
-        FTiming& OutTiming);
+        FTiming& OutTiming,
+        bool bBrickProgram = false,
+        int32 RequestedWorkerCount = WorkerCount);
 
     /** Count exact room/tunnel/core/passage candidate visits with instrumentation enabled. */
     FCandidateVisits CountCandidates(