Add PS_Editor plugin Phase 1: GameMode + Camera navigation

Runtime editor plugin with UE viewport-style camera controls:
- ZQSD/Arrows movement (always active), E/A for up/down
- LMB: pan (horizontal move + yaw), RMB: free fly look
- Alt+LMB / MMB: orbit around focal point, scroll: zoom
- HUD with controls help, cursor auto-hide during camera ops

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.claude/memory/MEMORY.md

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+- [PS_Editor plugin project](project_ps_editor.md) — Runtime editor plugin for UE 5.5, incremental dev, Phase 1 done
+- [Underscore naming](feedback_naming.md) — Always use PS_Editor_ prefix with underscores in file/class names
+- [UE5 build process](reference_build.md) — CLI build command for the project (Build.bat path, target name, flags)
+- [Build workflow](feedback_build_workflow.md) — Prefer Live Coding (Ctrl+Alt+F11) when UE is open, CLI build only when UE is closed

.claude/memory/feedback_build_workflow.md

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+---
+name: Build workflow preference
+description: User prefers Live Coding (Ctrl+Alt+F11) over CLI build when UE editor is open
+type: feedback
+---
+
+When UE editor is open, ask the user to do a Live Coding compile (Ctrl+Alt+F11) instead of trying CLI build. Only ask to close UE for a full rebuild when Live Coding is not sufficient (e.g., header changes that require UHT, new .generated.h files, Build.cs changes).
+
+**Why:** User finds Live Coding simpler and faster for iteration. CLI build fails when Live Coding is active.
+
+**How to apply:** After code changes, tell the user to press Ctrl+Alt+F11. If changes involve new UCLASS/USTRUCT/UENUM declarations, new files, or Build.cs modifications, warn that a full restart of UE + CLI build is needed instead.

.claude/memory/feedback_naming.md

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+---
+name: Underscore naming convention
+description: User requires PS_Editor_ prefix with underscores in all file and class names
+type: feedback
+---
+
+Keep the underscore in file and class names: PS_Editor_ prefix.
+
+**Why:** User explicitly corrected when I used PSEditor (camelCase) format. They want PS_Editor_GameMode, PS_Editor_Pawn, etc.
+
+**How to apply:** Always use PS_Editor_ prefix for any new file or class in the plugin. Never use PSEditor or PS_EditorXyz without the separating underscore.

.claude/memory/project_ps_editor.md

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+---
+name: PS_Editor plugin project
+description: Runtime editor plugin for UE 5.5 - object placement, scene editing, JSON save/load in packaged builds
+type: project
+---
+
+PS_Editor is a runtime editor plugin for Unreal Engine 5.5 that will be integrated into the PROSERVE project.
+
+**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
+- Naming: PS_Editor_ prefix on all files/classes
+- Plugin path: Unreal/Plugins/PS_Editor/

.claude/memory/reference_build.md

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+---
+name: UE5 build process
+description: How to build the PS_ProserveEditor UE 5.5 project from command line on Windows
+type: reference
+---
+
+UE 5.5 is installed at `C:\Program Files\Epic Games\UE_5.5` (found via registry key `HKLM\SOFTWARE\EpicGames\Unreal Engine\5.5`).
+
+Build command (Editor target, Development):
+```
+"C:/Program Files/Epic Games/UE_5.5/Engine/Build/BatchFiles/Build.bat" PS_ProserveEditorEditor Win64 Development -Project="C:/ASTERION/GIT/PS_ProserveEditor/Unreal/PS_ProserveEditor.uproject" -WaitMutex -FromMsBuild
+```
+
+**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.