Spawn System:
- SpawnableComponent: marker component for Blueprint actors (name, category, thumbnail)
- SpawnCatalog DataAsset: lists all spawnable Blueprints with Factory for easy creation
- SpawnManager: loads catalog, spawns actors in front of camera, ensures Movable mobility
- Reads metadata from Blueprint component templates (no temp spawn needed)
Catalogue UI:
- Left panel with scrollable list grouped by category
- Thumbnail cards (80x80) with name below, click to spawn
- "Capture All Thumbnails" button on DataAsset: auto-generates from UE thumbnails
Undo/Redo improvements:
- SpawnAction: undo hides spawned actor, redo shows it
- Delete confirmation dialog (Yes/No) before soft-delete
- Undo/redo auto-deselects hidden actors and refreshes gizmo
- Proper cleanup of hidden actors when actions pruned from stack
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>