wip(assembler): M2 round 3 -- opt-in hybrid sharp mesher (WorldAssemblerHybridV1) in the Unreal Core route

Default MarchingCubesV1 unchanged (W1/W8/W16 = round-6 hashes). Hybrid DC only in LOD0 interior cells
with tagged features; tile-border cells and LOD1+ stay MC. BuildHost: fixtures repeat exactly, cooked
collision bounds = render bounds, same-LOD borders pass, sampled SurfaceWorld cliff bit-identical to MC.
Open: tagged tiles cost 5.7-6.7x MC; corner-top field contact error 20 cm; 5 MC doorway LOD cases.

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

Source/VoxelForge/Public/VoxelWorld.h

@@ -72,6 +72,15 @@ enum class EVoxelAnchorPolicy : uint8
     FullVisual    UMETA(DisplayName = "Full Visual")       // rendered too (a second local viewpoint)
 };
 
+/** Versioned Core mesh recipe. Hybrid requires tagged sharp plan features and affects only Core meshes.
+ *  Recette de maillage Core versionnee. Hybrid exige des fonctions planaires balisees et ne touche qu'au Core. */
+UENUM(BlueprintType)
+enum class EVoxelForgeCoreMesherRecipe : uint8
+{
+    MarchingCubesV1 UMETA(DisplayName = "Marching Cubes V1"),
+    WorldAssemblerHybridV1 UMETA(DisplayName = "World Assembler Hybrid V1")
+};
+
 /** A non-player streaming center: keep a small box of level-0 tiles loaded around Actor so it has
  *  collision wherever it is. Plain internal struct (weak ptr is GC-safe without reflection). */
 struct FVoxelStreamingAnchor
@@ -269,6 +278,11 @@ public:
     UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Voxel World|Core", meta = (DisplayName = "Use VoxelForge Core"))
     bool bUseVoxelForgeCore = false;
 
+    /** Core-only, versioned mesher selection. Default keeps the existing Core hashes and geometry.
+     *  Recette reservee au Core; la valeur par defaut conserve les hachages et la geometrie actuels. */
+    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Voxel World|Core", meta = (DisplayName = "Core Mesher Recipe"))
+    EVoxelForgeCoreMesherRecipe CoreMesherRecipe = EVoxelForgeCoreMesherRecipe::MarchingCubesV1;
+
     /** Core-only clipmap radius, in level-0 Core tiles. Does not read Settings->ClipRadius. */
     UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Voxel World|Core", meta = (ClampMin = "1", ClampMax = "64"))
     int32 CoreClipRadius = 3;
@@ -330,6 +344,7 @@ public:
         uint64 CollisionSubmittedCycles = 0;
         uint64 CollisionSubmittedFrame = 0;
         bool bBodyUpdatedEventSeen = false;
+        bool bPooledComponent = false;
         uint64 BodyUpdatedEventCycles = 0;
         uint64 BodyUpdatedEventFrame = 0;
         bool bPhysicsStateReadyAtBodyUpdate = false;