Add route smoke tests

Elternbeirat.Web/Elternbeirat.Web.csproj

@@ -7,6 +7,12 @@
         <BlazorDisableThrowNavigationException>true</BlazorDisableThrowNavigationException>
     </PropertyGroup>
 
+    <!-- The test project uses WebApplicationFactory<Program>, which needs the
+         auto-generated Program class (internal with top-level statements). -->
+    <ItemGroup>
+        <InternalsVisibleTo Include="Elternbeirat.Web.Tests" />
+    </ItemGroup>
+
     <ItemGroup>
         <PackageReference Include="Markdig" Version="0.38.0" />
     </ItemGroup>