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/VerticalPartitionEditor/Private/VerticalPartitionCommandlet.cpp

@@ -0,0 +1,62 @@
+// Copyright IHY. Vertical Partition Streaming plugin (editor module).
+#include "VerticalPartitionCommandlet.h"
+#include "VerticalPartitionBuilder.h"
+#include "VerticalPartitionVolume.h"
+#include "VerticalPartitionLog.h"
+#include "EngineUtils.h"
+#include "Engine/World.h"
+#include "FileHelpers.h"
+#include "Misc/PackageName.h"
+#include "UObject/Package.h"
+
+UVerticalPartitionCommandlet::UVerticalPartitionCommandlet()
+{
+	IsClient = false;
+	IsServer = false;
+	IsEditor = true;
+	LogToConsole = true;
+}
+
+int32 UVerticalPartitionCommandlet::Main(const FString& Params)
+{
+	FString MapPath;
+	if (!FParse::Value(*Params, TEXT("Map="), MapPath) || MapPath.IsEmpty())
+	{
+		UE_LOG(LogVerticalPartition, Error, TEXT("[VP] Commandlet requires -Map=/Game/Maps/MyMap"));
+		return 1;
+	}
+
+	UE_LOG(LogVerticalPartition, Log, TEXT("[VP] Commandlet loading map %s ..."), *MapPath);
+	UWorld* World = UEditorLoadingAndSavingUtils::LoadMap(MapPath);
+	if (!World)
+	{
+		UE_LOG(LogVerticalPartition, Error, TEXT("[VP] Failed to load map %s"), *MapPath);
+		return 1;
+	}
+
+	AVerticalPartitionVolume* Volume = nullptr;
+	for (TActorIterator<AVerticalPartitionVolume> It(World); It; ++It)
+	{
+		Volume = *It;
+		break;
+	}
+	if (!Volume)
+	{
+		UE_LOG(LogVerticalPartition, Error, TEXT("[VP] No AVerticalPartitionVolume in %s"), *MapPath);
+		return 1;
+	}
+
+	FVerticalPartitionBuildReport Report;
+	const bool bOk = UVerticalPartitionBuilder::Build(Volume, Report);
+	UVerticalPartitionBuilder::DumpReport(Report, FPackageName::GetShortName(MapPath));
+
+	if (bOk)
+	{
+		TArray<UPackage*> ToSave;
+		ToSave.Add(World->GetOutermost());
+		FEditorFileUtils::PromptForCheckoutAndSave(ToSave, /*bCheckDirty*/false, /*bPromptToSave*/false);
+		UE_LOG(LogVerticalPartition, Log, TEXT("[VP] Commandlet build OK: %d cells."), Report.GeneratedCells);
+	}
+
+	return bOk ? 0 : 1;
+}