Scene split: MainMenu frontend + Game gameplay scenes; build/render settings

Add MainMenu.unity (build index 0, UITK frontend) alongside Game.unity (index 1); reorder EditorBuildSettings; URP/volume profile + project settings updates supporting the menu/game split.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ProjectSettings/ProjectSettings.asset

@@ -144,7 +144,8 @@ PlayerSettings:
   visionOSBundleVersion: 1.0
   tvOSBundleVersion: 1.0
   bundleVersion: 0.1.0
-  preloadedAssets: []
+  preloadedAssets:
+  - {fileID: 11400000, guid: 44cd3062bcdc07e43aaec59b78f224a6, type: 2}
   metroInputSource: 0
   wsaTransparentSwapchain: 0
   xboxOneDisableKinectGpuReservation: 1
@@ -522,7 +523,10 @@ PlayerSettings:
       m_Height: 720
       m_Kind: 1
       m_SubKind: 
-  m_BuildTargetBatching: []
+  m_BuildTargetBatching:
+  - m_BuildTarget: Standalone
+    m_StaticBatching: 1
+    m_DynamicBatching: 0
   m_BuildTargetShaderSettings: []
   m_BuildTargetGraphicsJobs: []
   m_BuildTargetGraphicsJobMode: []