Convert PocketBase dates to Berlin time; document code conventions

Elternbeirat.Web.Tests/PocketBaseClientTests.cs

@@ -23,14 +23,15 @@ public sealed class PocketBaseClientTests(PocketBaseFixture pocketBase)
     }
 
     [Fact]
-    public async Task Event_time_is_read_as_wall_clock_not_shifted()
+    public async Task Event_utc_is_converted_to_berlin_wall_clock()
     {
         var client = pocketBase.CreateClient();
 
         var events = await client.GetEventsAsync();
 
-        // The meeting is seeded as 19:30; by the timezone convention the number is
-        // taken at face value, so no shift to 20:30/21:30 happens.
+        // The meeting is seeded as 17:30Z. October is summer time (UTC+2), so the
+        // converter turns it into 19:30 Berlin wall-clock -- the time an editor
+        // entered in the admin form.
         var meeting = events.FirstOrDefault(e =>
             e.Title.Contains("Elternbeiratssitzung", StringComparison.Ordinal));
         meeting.ShouldNotBeNull();