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/OptimizerReconciler.h

@@ -0,0 +1,27 @@
+// Copyright IHY.
+#pragma once
+
+#include "CoreMinimal.h"
+
+namespace OptimizerReconciler
+{
+	/**
+	 * Compute the corrected world transform for the canonical mesh so it lands exactly where the
+	 * sibling currently sits. With D = CanonToMember (row-vector matrix) and W = sibling world
+	 * transform: W'_matrix = D * W_matrix (the verified formula).
+	 *
+	 * FTransform cannot represent shear; if the actor's non-uniform scale combined with D's rotation
+	 * produces shear, the reconstructed FTransform deviates from the exact matrix at the bbox corners.
+	 * We measure that deviation and reject (return false) when it exceeds ShearTol — the caller then
+	 * skips and reports the placement rather than silently corrupting it.
+	 *
+	 * @return false if the result shears (unrepresentable) — OutWprime is then not safe to apply.
+	 */
+	bool ComputeCorrectedWorld(
+		const FMatrix& CanonToMember,
+		const FTransform& W,
+		const FBox& CanonLocalBounds,
+		double ShearTol,
+		FTransform& OutWprime,
+		double& OutMaxCornerDev);
+}