Add Phase 3: object spawn system with catalogue UI

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>

.claude/memory/project_ps_editor.md

@@ -8,11 +8,35 @@ PS_Editor is a runtime editor plugin for Unreal Engine 5.5 that will be integrat
 
 **Why:** Enable runtime scene editing in packaged builds - place objects, configure properties, define scenarios, manipulate splines, modify lighting, and save/load scenes as JSON.
 
-**How to apply:** All development is incremental, phase by phase. Phase 1 = GameMode + Camera (completed). Future phases: object spawning/transform, JSON serialization, splines, lighting, AI characters.
-
 Key decisions:
-- UI: UMG driven by C++ (not Blueprints)
-- Gizmos: InteractiveToolsFramework (UE5 built-in)
-- Serialization: JSON via Json/JsonUtilities modules
+- UI: UMG driven by C++ (Slate)
+- Gizmos: Custom actor with BasicShapes + unlit material (InteractiveToolsFramework is editor-only)
+- Serialization: JSON via Json/JsonUtilities modules (future)
 - Naming: PS_Editor_ prefix on all files/classes
 - Plugin path: Unreal/Plugins/PS_Editor/
+- AZERTY keyboard layout: arrows + A/Q for movement, E/R/T for modes
+
+## Completed Phases
+
+### Phase 1 - GameMode + Camera
+- PS_Editor_GameMode, PS_Editor_Pawn, PS_Editor_PlayerController, PS_Editor_HUD
+- Camera: Fly (RMB), Pan (LMB drag), Orbit (Alt+LMB / MMB)
+- Movement: arrows + A (up) / Q (down)
+
+### Phase 2 - Selection + Transform + Undo
+- SelectionManager: raycast click-to-select, Ctrl+click multi-select, Movable actors only
+- Gizmo: custom actor with colored arrows (R/G/B), cones, SDPG_Foreground, constant screen size
+- Translate/Rotate/Scale via gizmo drag, hotkeys E/R/T
+- Snap to ground (End key), soft-delete (Delete key)
+- Undo/Redo system: custom UndoManager, Ctrl+Z / Ctrl+Y, 50 action stack
+- Properties panel: editable Location/Rotation/Scale fields
+- Toolbar: mode buttons + snap ground
+- Material: M_PS_Editor_Gizmo (Unlit, Vector Parameter "Color" → Emissive, Translucent, Disable Depth Test)
+
+## Next: Phase 3 - Object Spawning
+- Catalog/list of objects to place
+- Drag & drop or click to spawn
+- Duplication of existing objects
+
+## Next: Phase 4 - JSON Serialization
+- Save/load scenes as JSON

.claude/memory/reference_build.md

@@ -12,3 +12,7 @@ Build command (Editor target, Development):
 ```
 
 **How to apply:** Use this command to compile after code changes. Timeout should be set to 600000ms (10 min) for safety. The target name is `PS_ProserveEditorEditor` (Editor suffix) for editor builds.
+
+**When to use CLI vs Live Coding:**
+- Live Coding (Ctrl+Alt+F11): .cpp only changes (no new UCLASS, USTRUCT, UENUM, UPROPERTY in headers)
+- Full CLI build (UE must be closed): new files, header changes with new reflected types, Build.cs changes