fix(viewer): fresh signups start at tutorial_state=0, not 100

Previously RegisterAnonymousViewer auto-completed the tutorial, which
prevented the client from ever entering the tutorial flow. SeedViewerAsync
gains a tutorialState parameter (default 100) so existing tests keep
their pre-completed-tutorial assumption.

SVSim.UnitTests/Repositories/ViewerRepositoryTutorialDefaultTests.cs

@@ -0,0 +1,24 @@
+using Microsoft.Extensions.DependencyInjection;
+using NUnit.Framework;
+using SVSim.Database;
+using SVSim.Database.Repositories.Viewer;
+using SVSim.UnitTests.Infrastructure;
+
+namespace SVSim.UnitTests.Repositories;
+
+public class ViewerRepositoryTutorialDefaultTests
+{
+    [Test]
+    public async Task RegisterAnonymousViewer_starts_at_tutorial_step_0()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var repo = scope.ServiceProvider.GetRequiredService<IViewerRepository>();
+
+        var viewer = await repo.RegisterAnonymousViewer(Guid.NewGuid());
+
+        Assert.That(viewer.MissionData.TutorialState, Is.EqualTo(0),
+            "Fresh signups must start at PRE_TUTORIAL_STEP=0 so the client triggers the tutorial flow. " +
+            "Tests that want a pre-completed tutorial should use SeedViewerAsync (which defaults to 100).");
+    }
+}