standalone: 64 m full-detail override, detailed round tunnels, optional mesh cache -- generation itself NOT faster

ClipRadius override 3 (64 m at 25 cm). Uncached full detail 20.3 s on 8 workers (512 tiles at
~51 ms serial each should be ~3-4 s: the in-stream inefficiency is unsolved); full clipmap 170.6 s.
The 1 s / 5 s targets were met only from an on-disk mesh cache (.vfmesh, not committed) of
already-generated tiles: a revisit speed-up, not generation speed. Round tunnels gained
deterministic multi-scale wall relief and lost the larger mouth wedges (1.54% of lattice signs
changed, mean 0.20 m). Hashes stable across runs and 1 vs 6 workers.

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

Standalone/Research/VoxelSpeedRound/preliminary/before_l0_64.stdout.log

@@ -0,0 +1,7 @@
+[BenchmarkConfig] tile_cache_window=1 fused_min_lod=3 room_graph_cache_slots=1 command='--benchmark-level=0 --benchmark-count=64 --profile-attribution --density-hash'
+[TileBenchmark] LOD=0 generated=64 samples=2.74M worker_sum=3.400s avg=53.123ms p50=53.975ms p95=65.668ms vertices=68317 indices=390195 profiling=Attribution
+[TileDensityHash] LOD=0 tiles=64 hash=0x3d31a090650399d3
+[TileProfile] LOD=0 GetDensityAt=3396.306ms ApplyDisturbances=0.381ms PassageModifier=0.440ms PassageLandingAir=0.392ms PassageLandingFloor=0.911ms PassageLandingRoomFloor=0.062ms PassageStructuralPosts=0.425ms StructuralTail=5.714ms FusedEvaluator=38.837ms RoomGraphBuild=24.652ms RoomGraphSdf=6.418ms TunnelCoreWorld=9.514ms FusedDetail=1.215ms FusedStructural=1.905ms DensityPrologue=0.809ms DensityCore=40.115ms DensityDisturbances=1.122ms DensityStructuralPosts=6.895ms DensityBoundarySeal=0.397ms DensityDiffLayer=0.377ms DensityTail=0.398ms MesherGenerateMesh=3397.194ms MesherDensityGrid=3362.267ms MesherCellClassification=33.526ms MesherGradientNormals=1.933ms MesherVertexInterpolation=1.912ms MesherStreamBuilding=14.733ms MesherOther=3.094ms
+[TileCounters] sdf_builds=33 graph_tile_builds=33 graph_core_builds=0 op_block_builds=0
+[SdfRebuildCauses] strate=1 seed=0 fingerprint=1 layout=1 manager=1 terrain_ops=1 fused_policy=1 tile_policy=0 tile_identity=0 bounds_x=10 bounds_y=25 tile_window_accepted=0 tile_window_rejected=0
+[TilePolicyKeyChanges] origin=64 step=1 cells=1 fingerprint=1 layout=1 manager=1 terrain_ops=1 fused_path=1 context=0