Add a mobile nav and pin the header while scrolling

Elternbeirat.Web.Tests/PocketBaseClientTests.cs

@@ -85,7 +85,9 @@ public sealed class PocketBaseClientTests(PocketBaseFixture pocketBase)
 
         var home = pages.Single(p => p.Slug == "home");
         home.Embed.ShouldBe(["posts", "events"], ignoreOrder: true);
-        home.Location.ShouldBe("header");
+        // Home has no menu slot: the brand is the home link, so a "Start" nav
+        // entry would be redundant. NavBuilder filters it out via this empty value.
+        home.Location.ShouldBe("");
     }
 
     [Fact]

Elternbeirat.Web.Tests/PocketBaseFixture.cs

@@ -222,10 +222,12 @@ public sealed class PocketBaseFixture : IAsyncLifetime
         // Pages that the route smoke tests reach through the navigation, the
         // footer or the FAQ hub. Header pages carry a location+order; the FAQ
         // sub-pages are plain content pages without a menu slot. All public.
+        // The home page has no menu slot (location ""): the site brand is the home
+        // link, so a separate "Start" nav entry would be redundant.
         await CreateRecordAsync(http, "pages", new
         {
-            title = "Startseite", body = "# Willkommen", location = "header",
-            order = 1, slug = "home", embed = new[] { "posts", "events" }, @public = true,
+            title = "Startseite", body = "# Willkommen", location = "",
+            order = 0, slug = "home", embed = new[] { "posts", "events" }, @public = true,
         });
         await CreateRecordAsync(http, "pages", new
         {