Add alpha session gate with cookie auth and login UI.

tests/HSchool.AppHost.Tests/ServiceabilityTests.cs

@@ -117,6 +117,7 @@ public class ServiceabilityTests(AppHostFixture fixture)
     public async Task Dump_UnknownSchool_IsNotFound()
     {
         using var client = fixture.App.CreateHttpClient("server");
+        await SchoolApiTests.LoginAsync(client);
 
         using var response = await client.GetAsync("/api/dev/schools/999999/dump", TestContext.Current.CancellationToken);
         Assert.Equal(HttpStatusCode.NotFound, response.StatusCode);