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();

Elternbeirat.Web.Tests/PocketBaseFixture.cs

@@ -295,15 +295,18 @@ public sealed class PocketBaseFixture : IAsyncLifetime
             body = "Text", slug = "new-hall", @public = true,
         });
 
-        // Events: the meeting carries the wall-clock time the timezone test checks.
+        // Events: PocketBase stores UTC. The meeting is 19:30 Berlin; October is
+        // summer time (UTC+2), so it is stored as 17:30Z and the timezone test
+        // expects 19:30 back. The Herbstbasar is 09:00-13:00 Berlin in November
+        // (winter, UTC+1), stored as 08:00Z-12:00Z.
         await CreateRecordAsync(http, "events", new
         {
-            start = "2026-10-08 19:30:00.000Z", title = "Elternbeiratssitzung",
+            start = "2026-10-08 17:30:00.000Z", title = "Elternbeiratssitzung",
             location = "Aula", note = "", @public = true,
         });
         await CreateRecordAsync(http, "events", new
         {
-            start = "2026-11-22 09:00:00.000Z", end = "2026-11-22 13:00:00.000Z",
+            start = "2026-11-22 08:00:00.000Z", end = "2026-11-22 12:00:00.000Z",
             title = "Herbstbasar", location = "Schulhof", note = "", @public = true,
         });