fix(viewer): RegisterViewer defaults to post-tutorial TutorialState=100

BuildDefaultViewer hardcoded TutorialState=1 — correct for fresh anonymous
signups (RegisterAnonymousViewer) but wrong for AdminController.ImportViewer
and Steam-social signups, which both go through RegisterViewer and expect a
prod-replica viewer that boots to the home screen. Add an initialTutorialState
parameter (default 1 preserves RegisterAnonymousViewer behavior); RegisterViewer
passes 100.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.UnitTests/Repositories/ViewerRepositoryTests.cs

@@ -141,6 +141,24 @@ public class ViewerRepositoryTests
             await repo.RegisterAnonymousViewer(Guid.Empty));
     }
 
+    [Test]
+    public async Task RegisterViewer_starts_at_post_tutorial_state()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var repo = scope.ServiceProvider.GetRequiredService<IViewerRepository>();
+
+        var viewer = await repo.RegisterViewer(
+            "Imported Viewer",
+            SVSim.Database.Enums.SocialAccountType.Steam,
+            socialAccountIdentifier: 76_561_198_000_000_999UL);
+
+        Assert.That(viewer.MissionData.TutorialState, Is.EqualTo(100),
+            "RegisterViewer (admin-import + Steam-social signup) must produce a post-tutorial " +
+            "viewer by default. Import requests can override via request.TutorialState; absence " +
+            "means 'a prod-replica viewer ready for the home screen', NOT 'replay tutorial'.");
+    }
+
     [Test]
     public async Task GetViewerByUdid_returns_viewer_or_null()
     {