- Add close button (X) in title bar with save confirmation overlay
- Add OnEditorClosed delegate on PlayerController (BP-bindable)
- Add OnPropertiesLoaded event to EditableInterface (fires after scene load)
- Add IsLoadingFromScene() helper for BP BeginPlay skip pattern
- ComputeSpawnLocation now raycasts to avoid spawning through floors
- Track dirty state for save confirmation on close
- Scene load uses PS_Editor_Loading tag via CustomPreSpawnInitalization
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>