Mesh Optimizer: sibling StaticMesh duplicate remover (UE 5.7)

Editor plugin that detects geometrically-identical sibling StaticMeshes across a
level, rebases each placement onto one canonical mesh with a corrected transform
(W' = D * W, verified by exact vertex matching), and can collapse groups into HISM.
Native Slate tool panel + BlueprintCallable UOptimizerSubsystem.

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

Source/OptimizerEditor/Private/SOptimizerPanel.h

@@ -0,0 +1,40 @@
+// Copyright IHY.
+#pragma once
+
+#include "CoreMinimal.h"
+#include "Widgets/SCompoundWidget.h"
+
+class STextBlock;
+class SCheckBox;
+class SWidget;
+
+/**
+ * Native Slate panel for the Mesh Optimizer (hosted in a nomad tab). Drives UOptimizerSubsystem:
+ * Scan (dry-run report) / Unify (reassign siblings) / Build HISM (collapse). Uses editor styling
+ * so it reads as a native tool rather than raw UMG.
+ */
+class SOptimizerPanel : public SCompoundWidget
+{
+public:
+	SLATE_BEGIN_ARGS(SOptimizerPanel) {}
+	SLATE_END_ARGS()
+
+	void Construct(const FArguments& InArgs);
+
+private:
+	TSharedRef<SWidget> MakeLabeledCheck(TSharedPtr<SCheckBox>& Out, const FText& Label, bool bDefault);
+	TSharedRef<SWidget> MakeButton(const FText& Label, FOnClicked OnClicked);
+
+	FReply OnScan();
+	FReply OnUnify();
+	FReply OnBuildHISM();
+
+	void SetReport(const FString& Text);
+	bool IsChecked(const TSharedPtr<SCheckBox>& Chk) const;
+
+	TSharedPtr<SCheckBox> ChkMirror;
+	TSharedPtr<SCheckBox> ChkScale;
+	TSharedPtr<SCheckBox> ChkMergeMat;
+	TSharedPtr<SCheckBox> ChkDestroy;
+	TSharedPtr<STextBlock> ResultsBox;
+};