Initial commit: Vertical Partition Streaming plugin (UE 5.7)

Bounded vertical route partition / streaming for handcrafted spiral climb maps
(Only Up / Only Climb). Not World Partition, not Level Instances as core arch.

- Z-cell segmentation + optional XY subcells, editor builder + commandlet
- NonDestructive visibility backend + streaming-level backend
- Offline HLOD proxies: MergedMesh / SimplifiedProxy (ProxyLOD)
- Universal Level Instance + Packed Level Actor + HISM support (flatten+merge)
- Vertical-aware runtime streamer (full/preload/HLOD/unload, hysteresis,
  velocity prediction, fall-risk), WP-style debug viz + vp.* console
- Safe-by-default: only static decor streams; sky/lights/gameplay stay persistent

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Source/VerticalPartition/Public/VerticalPartitionDescriptor.h

@@ -0,0 +1,50 @@
+// Copyright IHY. Vertical Partition Streaming plugin.
+//
+// The build artifact: a data asset describing every generated cell plus a snapshot
+// of the settings and volume bounds the build was run with. The runtime streamer
+// consumes this; the editor builder produces it.
+#pragma once
+
+#include "CoreMinimal.h"
+#include "Engine/DataAsset.h"
+#include "VerticalPartitionTypes.h"
+#include "VerticalPartitionDescriptor.generated.h"
+
+UCLASS(BlueprintType)
+class VERTICALPARTITION_API UVerticalPartitionDescriptor : public UDataAsset
+{
+	GENERATED_BODY()
+
+public:
+	/** Map this descriptor was built from (for rebuild / out-of-date checks). */
+	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category="VerticalPartition")
+	FSoftObjectPath SourceLevel;
+
+	/** Settings snapshot used at build time (runtime ranges may be overridden live). */
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category="VerticalPartition")
+	FVerticalPartitionSettings Settings;
+
+	/** World bounds of the partition volume at build time. */
+	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category="VerticalPartition")
+	FBox VolumeBounds = FBox(ForceInit);
+
+	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category="VerticalPartition")
+	EVerticalConversionMode BuiltMode = EVerticalConversionMode::NonDestructive;
+
+	/** Content hash of the source actors at build time (for incremental rebuild). */
+	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category="VerticalPartition")
+	int64 SourceContentHash = 0;
+
+	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category="VerticalPartition")
+	TArray<FVerticalCellDescriptor> Cells;
+
+	/** Last build report (kept for the UI / Dump Report). */
+	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category="VerticalPartition")
+	FVerticalPartitionBuildReport LastReport;
+
+	/** Find a cell descriptor by id. Returns nullptr if absent. */
+	const FVerticalCellDescriptor* FindCell(const FVerticalCellId& Id) const;
+	int32 FindCellIndex(const FVerticalCellId& Id) const;
+
+	bool HasFullPackages() const;
+};