Add TestMap, test actor asset, update DefaultEngine.ini and memory

- DefaultEngine.ini: set GameDefaultMap + EditorStartupMap to TestMap
  (API key stripped — set locally via Project Settings, not committed)
- Content/TestMap.umap: initial test level
- Content/test_AI_Actor.uasset: initial test actor
- .claude/MEMORY.md: document API key handling, add memory file index,
  note private git server and TestMap as default map

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Unreal/PS_AI_Agent/Config/DefaultEngine.ini

@@ -1,7 +1,8 @@
 
 
 [/Script/EngineSettings.GameMapsSettings]
-GameDefaultMap=/Engine/Maps/Templates/OpenWorld
+GameDefaultMap=/Game/TestMap.TestMap
+EditorStartupMap=/Game/TestMap.TestMap
 
 [/Script/Engine.RendererSettings]
 r.AllowStaticLighting=False
@@ -90,3 +91,4 @@ ConnectionType=USBOnly
 bUseManualIPAddress=False
 ManualIPAddress=
 
+