Add home hero with intro and buttons from the body, next-event card and page tiles

Elternbeirat.Web/Program.cs

@@ -8,6 +8,10 @@ var builder = WebApplication.CreateBuilder(args);
 
 builder.Services.AddRazorComponents();
 
+// "Today" for upcoming events comes from this clock, not DateTime.Today, so the
+// smoke tests can swap in a fixed date and check the pages before and after an event.
+builder.Services.AddSingleton(TimeProvider.System);
+
 // The typed client reads content from PocketBase over its REST API. The base URL
 // comes from config: appsettings for local dev, the PocketBase__BaseUrl env var
 // on the server (see compose.yaml).