Add Main Menu UI, alien models & editor configs

Add VS Code workspace/launch/settings for Unity development and a new MainMenu scene/UI (uxml, uss, tss) with MainMenuController and related assets. Import two alien character FBX models (with generated .meta settings) and add folder metadata. Update Git LFS pointers for a Game Kit scene and add modifications to Game Kit Controller assets (World Canvas material and Save Camera render texture) and ProjectSettings/QualitySettings. These changes bring initial UI/menu assets and character models into the project and add editor tooling/config for easier development.

Assets/Game Kit Controller/Shaders/World Canvas.mat

@@ -26,6 +26,7 @@ Material:
   m_ModifiedSerializedProperties: 0
   m_ValidKeywords:
   - _ALPHAPREMULTIPLY_ON
+  - _SPECULAR_COLOR
   - _SURFACE_TYPE_TRANSPARENT
   m_InvalidKeywords: []
   m_LightmapFlags: 4
@@ -37,7 +38,6 @@ Material:
   disabledShaderPasses:
   - MOTIONVECTORS
   - DepthOnly
-  - SHADOWCASTER
   m_LockedProperties: 
   m_SavedProperties:
     serializedVersion: 3
@@ -158,7 +158,6 @@ Material:
     - _Surface: 1
     - _UVSec: 0
     - _UseUIAlphaClip: 0
-    - _XRMotionVectorsPass: 1
     - _ZWrite: 0
     m_Colors:
     - _BaseColor: {r: 1, g: 1, b: 1, a: 1}