wip(assembler): M1 round 5 -- native SurfaceWorld manifest delivered into the Unreal Core route

Manifest imported into UVoxelSettings (hash 8933693d9560ba9f), folded into the season
content hash only when Core is on. BuildHost: W1/W8/W16 stable, 2553 surface tiles match
standalone, 432 LOD transitions, collision on all 36 expected tiles. Matched timing
96.8 s native vs 197.3 s bridge (2.04x). Collision support tiles wait for Core region admission.

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

Source/VoxelForge/Public/VoxelSettings.h

@@ -28,6 +28,14 @@ public:
     float GetEffectiveWorldRadiusVoxels() const;
     int32 GetEffectiveSeasonNumber() const;
 
+    /** Import a reviewed native SurfaceWorld plan; empty preserves the existing Core/legacy routes. */
+    VOXELFORGE_API bool SetWorldAssemblyManifestJson(const FString& InJson, FString& OutReport);
+    VOXELFORGE_API bool GetWorldAssemblyManifestJson(FString& OutCanonicalJson, FString& OutContentHash,
+                                                     FString& OutError) const;
+
+    UFUNCTION(CallInEditor, Category = "Voxel|Strates")
+    void ImportWorldAssemblyManifestJson();
+
 	//=========================================================================
 	// STREAMING (distance de vue)
 	//=========================================================================
@@ -365,6 +373,21 @@ public:
 	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Voxel|Strates")
 	TSoftObjectPtr<UVoxelSeasonAsset> Season;
 
+    // Optional reviewed Core surface plan. The canonical JSON stays in this cooked settings asset;
+    // its Core FNV digest is included in GetCurrentSeasonContentHash when present.
+    // Plan de surface Core facultatif; le JSON canonique est cuit avec les reglages et son hash
+    // Core est inclus dans GetCurrentSeasonContentHash lorsqu'il est present.
+    UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Voxel|Strates", meta = (MultiLine = true))
+    FString WorldAssemblyManifestJson;
+
+    UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Voxel|Strates")
+    FString WorldAssemblyManifestHash;
+
+#if WITH_EDITORONLY_DATA
+    UPROPERTY(EditAnywhere, Category = "Voxel|Strates|World Assembly", meta = (FilePathFilter = "json"))
+    FFilePath SourceWorldAssemblyManifestJson;
+#endif
+
 	// Numéro de saison (incrementé par ChangeSeed). Purement informatif côté gameplay.
 	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Voxel|Strates")
 	int32 CurrentSeason = 1;