Write what N1MM needs before it will open a log

Checked by opening a log this program wrote in N1MM 1.0.11031. Three things it
rejected:

- a log naming a contest with no row in the Contest table throws "No current
  row" in Contest.FromRow, so the definition row is written whenever a contest
  is opened;
- an empty overlay category is answered with "Invalid Overlay Category:", so an
  entry with no overlay now says "N/A", and the dialog offers N1MM's list;
- the sent exchange omits the report, which is what N1MM's own contest dialog
  asks for.

With those three fixed N1MM opens the log and shows the contacts.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/Nonemm.App/AppSession.cs

@@ -92,11 +92,17 @@ public sealed class AppSession : IDisposable
         return stored;
     }
 
+    /// N1MM reads the `Contest` table when it opens a log, so the definition is
+    /// written again whenever a contest is opened, not only when it is created.
+    private void SaveDefinition(Contest contest) =>
+        Store.SaveContestDefinition(ContestDefinitions.For(contest));
+
     public void OpenContest(int contestNumber)
     {
         ContestInstance instance = Store.Contest(contestNumber)
             ?? throw new InvalidOperationException($"no contest numbered {contestNumber} in the log");
         Contest contest = Registry.Create(instance.ContestName, ModeCategoryOf(instance));
+        SaveDefinition(contest);
         Logging = new LoggingSession(Store, contest, instance, Settings.Station.ToStationInfo(), Countries);
         Logging.Changed += (_, _) => Changed?.Invoke(this, EventArgs.Empty);
         Logging.Logged += (_, qso) => Bandmap.Add(new Spot(