Add post and event cards, shared calendar sheet and per-event ICS; rework past events and next-event card

Elternbeirat.Web/Features/Events/CalendarSheet.razor.cs

@@ -0,0 +1,22 @@
+using Microsoft.AspNetCore.Components;
+
+namespace Elternbeirat.Web.Features.Events;
+
+/// <summary>
+///     Renders an event's start day as a calendar sheet (month, day, weekday).
+/// </summary>
+/// <remarks>
+///     One component for every place that shows an event (the next-event card on the
+///     home page, the events embed and the events page), so the sheets look the same
+///     everywhere. The texts come from <see cref="EventDateFormat"/>.
+/// </remarks>
+/// <seealso cref="EventCard"/>
+public partial class CalendarSheet
+{
+    /// <summary>
+    ///     The event's start, as Berlin wall-clock time.
+    /// </summary>
+    [Parameter]
+    [EditorRequired]
+    public DateTime Value { get; set; }
+}