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>

.gitignore

@@ -0,0 +1,11 @@
+# Unreal Engine build artifacts
+Binaries/
+Intermediate/
+DerivedDataCache/
+Saved/
+
+# IDE / OS
+.vs/
+*.pdb
+*.VC.db
+.DS_Store