measure(perf): per-component ablation of the TunnelNetwork path; exact worms restored

Round (Codex; reviewed by me against PERF-SAMPLED.md).

Revert: voxel.WormNoiseMode / voxel.WormLatticeStep, their storage and their switches are
REMOVED. VoxelWormField has one path again, exact Perlin with the N1 short circuit. Kept:
bEnableWorms (asset), WormsForceOff (measurement only), the exact block skip (default 0).

Ablation instrument: 14 development-only, world-changing force-off bits (voxel.TunnelAblate*),
applied on the fused, op-stack/classifier, cached SDF/core and modifier/floor paths. They resolve
once per process, are hashed into the generation fingerprint, and are compiled to zero in
UE_BUILD_SHIPPING (VoxelDensityAblation.cpp). They are a measurement instrument, never a gameplay
or multiplayer switch.

Defaults exact: canonical export OBJ b3e5f4c3..9b377, worms-region 311CA42C / 75,482 triangles,
capability 20,830 / 10,909, and 841/841 keyed tiles identical to NextHeadStaticTrace_20260913.

Static worker seconds saved by removing ONE component (two off runs vs the interleaved all-on
33.06 s; baseline noise 0.27%):
  tunnel SDF 11.4%, cave warp 10.3%, passage carving 10.1%, landing posts 9.9%,
  passage structural posts 5.6%, worms 2.4%, native floor 2.2%, origin spine 1.6%,
  room SDF 1.6%, everything else <= 1.1%
Moving (2+2 runs each) confirms the top five at 6.0-11.6%. Tunnel SDF off cuts LOD0 generation
p95 104 -> 83 ms: it owns the slow tail. The positive savings sum to 58% of the static total; the
other 42% is shared. The rows are not additive.

Unexplained: tunnel-core OFF made the static total 2.9x SLOWER (95.5 s) while LOD0 generation got
faster (p50 64.7 -> 60.6 ms) and triangles fell. The report blames the changed field, which does
not fit; more likely a slow fallback path in coarse tiles. That row is not a cost measurement.

Ledger: every Unreal process exited 0 and verified the loaded DLL; two PowerShell parser errors
happened before any process started. No crashes or retries.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TaFdXhTdYMkW1xrV6ApT6Y

Source/VoxelForgeEditor/Private/VoxelForgeExploreCommandlet.cpp

@@ -29,11 +29,11 @@
 #include "VoxelCaveMorphology.h"
 #include "VoxelDiffLayer.h"
 #include "VoxelDensityOpStack.h"
+#include "VoxelDensityAblation.h"
 #include "VoxelDensityProfile.h"
 #include "VoxelGenerator.h"
 #include "VoxelMarchingCubesMesher.h"
 #include "VoxelNoise.h"
-#include "VoxelWormField.h"
 #include "VoxelSettings.h"
 #include "VoxelStackSampler.h"
 #include "VoxelStrateDefinition.h"
@@ -4202,8 +4202,8 @@ FString BuildManifestJson(
     {
         Writer->WriteValue(TEXT("worm_strength"), static_cast<double>(Arguments.WormStrength));
     }
-    Writer->WriteValue(TEXT("worm_lattice_step"), VoxelWormField::GetLatticeStep());
-    Writer->WriteValue(TEXT("worm_noise_mode"), VoxelWormField::GetNoiseMode());
+    Writer->WriteValue(TEXT("tunnel_ablation_mask"),
+        static_cast<int64>(VoxelDensityAblation::GetResolvedMask()));
     WriteTunnelFloorOverrides(*Writer, Arguments);
     Writer->WriteValue(TEXT("room_mouth_rise_override"), Arguments.bRoomMouthRiseOverride);
     if (Arguments.bRoomMouthRiseOverride)
@@ -4478,8 +4478,8 @@ FString BuildExploreJson(
     {
         Writer->WriteValue(TEXT("worm_strength"), static_cast<double>(Arguments.WormStrength));
     }
-    Writer->WriteValue(TEXT("worm_lattice_step"), VoxelWormField::GetLatticeStep());
-    Writer->WriteValue(TEXT("worm_noise_mode"), VoxelWormField::GetNoiseMode());
+    Writer->WriteValue(TEXT("tunnel_ablation_mask"),
+        static_cast<int64>(VoxelDensityAblation::GetResolvedMask()));
     WriteTunnelFloorOverrides(*Writer, Arguments);
     Writer->WriteValue(TEXT("room_mouth_rise_override"), Arguments.bRoomMouthRiseOverride);
     if (Arguments.bRoomMouthRiseOverride)