port(m1): wave 6c — Unity + Steam/FB/Adjust static-class shims (696->572)

Off-battle-path static surfaces (CS0103 cluster):
- UnityStatics: Gizmos, Physics2D, Caching, GUIUtility, Cursor, ColorUtility,
  ScreenCapture, RenderSettings, JsonUtility, Social + CursorLockMode enum.
- RaycastHit2D implicit-bool operator; ILocalUser in SocialPlatforms.
- Steamworks: Callback<T>.Create, AppId_t/CSteamID/HAuthTicket/SteamNetworkingIdentity,
  MicroTxn/GetAuthSessionTicket response structs, SteamAPI/User/Utils/Client statics.
  Removed empty dup GetAuthSessionTicketResponse_t from ThirdParty.cs.
- Facebook.Unity: FB + ILoginResult + FacebookDelegate<T>; com.adjust.sdk.Adjust;
  global TimeNativePlugin/Packsize native-plugin stubs.

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

SVSim.BattleEngine/Shim/UnityEngine/UnityShim2.cs

@@ -65,4 +65,5 @@ namespace UnityEngine.SocialPlatforms
     // Cute.IAchievementCallback; adding one here makes the unqualified name ambiguous.
     public interface IAchievement { }
     public interface IAchievementDescription { }
+    public interface ILocalUser { void Authenticate(System.Action<bool> callback); }
 }