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/VoxelForge/Public/VoxelDensityPrimitives.h

@@ -27,6 +27,7 @@
 #include "CoreMinimal.h"
 #include "VoxelTypes.h"   // SmoothStep01
 #include "VoxelPassageGeometry.h" // shared body-sized landing/tunnel geometry
+#include "VoxelDensityAblation.h" // development-only world-changing measurements
 
 //=============================================================================
 // SEAL DE FRONTIÈRE / BOUNDARY SEAL
@@ -43,7 +44,7 @@ FORCEINLINE void VF_ApplyBoundarySeal(float& Density, float WorldZ,
     float StrateTopZ, float StrateBottomZ,
     float Thickness, float BaseDensity)
 {
-    if (Thickness <= 0.0f) return;
+    if (VoxelDensityAblation::IsBoundarySealOff() || Thickness <= 0.0f) return;
 
     const float DistTop = StrateTopZ - WorldZ;     // + si on est sous le plafond
     const float DistBot = WorldZ - StrateBottomZ;  // + si on est au-dessus du sol
@@ -71,6 +72,7 @@ FORCEINLINE void VF_ApplyBoundarySeal(float& Density, float WorldZ,
 FORCEINLINE void VF_ApplyPassageCarving(float& Density, float ModSDF,
     float BaseDensity, float SealThickness)
 {
+    if (VoxelDensityAblation::IsPassageCarvingOff()) return;
     constexpr float PASSAGE_BLEND_RADIUS = 4.0f;
     if (ModSDF >= PASSAGE_BLEND_RADIUS) return;
 
@@ -121,7 +123,7 @@ FORCEINLINE void VF_ApplyPassageLandingCarving(float& Density, float LandingSDF,
 FORCEINLINE void VF_ApplyOriginSpine(float& Density, float WorldX, float WorldY, float WorldZ,
     float StrateTopZ, float StrateBottomZ, float SealThickness, float BaseDensity, float Radius)
 {
-    if (Radius <= 0.0f) return;
+    if (VoxelDensityAblation::IsOriginSpineOff() || Radius <= 0.0f) return;
 
     const VoxelPassageGeometry::FOriginLandingGeometry Geometry =
         VoxelPassageGeometry::BuildOriginLandingGeometry(
@@ -153,7 +155,7 @@ FORCEINLINE void VF_ApplyOriginLandingAir(float& Density,
     float WorldX, float WorldY, float WorldZ,
     float StrateTopZ, float StrateBottomZ, float SealThickness, float BaseDensity, float Radius)
 {
-    if (Radius <= 0.0f) return;
+    if (VoxelDensityAblation::IsLandingPostsOff() || Radius <= 0.0f) return;
     const VoxelPassageGeometry::FOriginLandingGeometry Geometry =
         VoxelPassageGeometry::BuildOriginLandingGeometry(
             StrateTopZ, StrateBottomZ, SealThickness, Radius);
@@ -169,7 +171,7 @@ FORCEINLINE void VF_ApplyOriginLandingFloor(float& Density,
     float WorldX, float WorldY, float WorldZ,
     float StrateTopZ, float StrateBottomZ, float SealThickness, float BaseDensity, float Radius)
 {
-    if (Radius <= 0.0f) return;
+    if (VoxelDensityAblation::IsLandingPostsOff() || Radius <= 0.0f) return;
     const VoxelPassageGeometry::FOriginLandingGeometry Geometry =
         VoxelPassageGeometry::BuildOriginLandingGeometry(
             StrateTopZ, StrateBottomZ, SealThickness, Radius);
@@ -221,7 +223,8 @@ FORCEINLINE void VF_ApplyOriginLandingFloorMC(float& Density,
 FORCEINLINE void VF_ApplyXYEdgeSeal(float& Density, float WorldX, float WorldY,
     float WorldRadiusVoxels, float Thickness, float BaseDensity)
 {
-    if (!(WorldRadiusVoxels > 0.0f) || !(Thickness > 0.0f) || !(BaseDensity > 0.0f)) return;
+    if (VoxelDensityAblation::IsXYEdgeSealOff()
+        || !(WorldRadiusVoxels > 0.0f) || !(Thickness > 0.0f) || !(BaseDensity > 0.0f)) return;
     if (!VoxelMath::IsFinite(WorldX) || !VoxelMath::IsFinite(WorldY)
         || !VoxelMath::IsFinite(WorldRadiusVoxels) || !VoxelMath::IsFinite(Thickness)
         || !VoxelMath::IsFinite(BaseDensity)) return;
@@ -256,7 +259,8 @@ FORCEINLINE void VF_ApplyXYEdgeSeal(float& Density, float WorldX, float WorldY,
 FORCEINLINE void VF_ApplyXYEdgeSealMC(float& Density, float WorldX, float WorldY,
     float WorldRadiusVoxels, float Thickness, float BaseDensity)
 {
-    if (!(WorldRadiusVoxels > 0.0f) || !(Thickness > 0.0f)) return;
+    if (VoxelDensityAblation::IsXYEdgeSealOff()
+        || !(WorldRadiusVoxels > 0.0f) || !(Thickness > 0.0f)) return;
 
     float InternalDensity = -Density;
     VF_ApplyXYEdgeSeal(InternalDensity, WorldX, WorldY,