Add empty test level and Unreal MCP tooling

- L_TestFlight: empty, zero-gravity level for Phase 0 flight testing,
  set as editor/game default map.
- Enable UnrealMCPython + Python Editor Script Plugin, third-party
  MCP plugin (GenOrca/unreal-mcp v2.2.0) giving direct editor control
  (actors, blueprints, levels, materials, etc.) alongside Epic's
  built-in Unreal MCP plugin.
- Vendor the mcp-server Python source used to bridge to the plugin.
- .mcp.json intentionally gitignored (machine-specific absolute paths).

Config/DefaultEngine.ini

@@ -1,7 +1,8 @@
 
 
 [/Script/EngineSettings.GameMapsSettings]
-GameDefaultMap=/Engine/Maps/Templates/OpenWorld
+GameDefaultMap=/Game/Maps/L_TestFlight
+EditorStartupMap=/Game/Maps/L_TestFlight
 
 [/Script/Engine.RendererSettings]
 r.AllowStaticLighting=False