Mark a dupe in the contact type column, as N1MM does

N1MM writes a contact type on every contact it logs: `D` for a station
already worked, `N` for one the entry may not work at all, and empty for an
ordinary contact. Nothing here wrote the column, so a dupe counted as a
contact worth no points instead of dropping out of the score, and the two
places that read the column did nothing: the QTC pile offered dupes that
N1MM leaves out, and the statistics window could not leave dupes out either.

The marking is in one place, `ContestLog.ApplyVerdict`, and every contest is
marked the same way. What changes between contests is what counts as a dupe
and which stations are workable, and both come from the contest, as they do
in N1MM's `Contact.IsDupe`. No contest module in N1MM marks differently. Our
own callsign is not workable either, which is what N1MM adds on top of the
contest rule.

Two details follow N1MM as well: QTC traffic keeps an empty column, because
its `IsDupe` only marks a row while the program is logging contacts; and a
mark that came with the contact stands, because N1MM marks a contact when it
logs or edits one and never clears marks in a pass over the log. Editing a
contact clears the column so it is worked out again, which is what N1MM does
at the same point: an edit can move a contact to a band where it is no
longer a dupe.

A dupe is now out of the score altogether — contacts, points and multipliers
— which is N1MM's `ScoreClass.AddContact`. The QSO count still counts WAE
QTC rows as contacts; that is the other half of the scoring audit's item 14.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0157i7PiZyqBkquxS9A6FTdQ

src/Nonemm.Contests/ContestLog.cs

@@ -170,8 +170,41 @@ public sealed class ContestLog
             History = History,
         };
 
-    private static Qso ApplyVerdict(Qso qso, Verdict verdict) =>
-        ApplyMultiplierFlags(qso, verdict.NewMultipliers) with { Points = verdict.Points };
+    private Qso ApplyVerdict(Qso qso, Verdict verdict) =>
+        ApplyMultiplierFlags(qso, verdict.NewMultipliers) with
+        {
+            Points = verdict.Points,
+            ContactType = ContactTypeOf(qso),
+        };
+
+    /// N1MM's contact type column, which it writes in `Contact.IsDupe`: `D`
+    /// for a station already worked, `N` for one this entry may not work at
+    /// all, and empty for an ordinary contact. Every contest is marked the
+    /// same way; what changes between them is what counts as a dupe and which
+    /// stations are workable, and both of those come from the contest here as
+    /// they do there.
+    ///
+    /// Traffic keeps an empty column, which is what N1MM's QTC window writes:
+    /// its `IsDupe` only marks a row while the program is logging contacts.
+    private string ContactTypeOf(Qso qso)
+    {
+        if (!contest.IsContact(qso))
+        {
+            return "";
+        }
+        // a mark that came with the contact stands: N1MM marks a contact when
+        // it logs or edits it and never clears the mark in a pass over the
+        // log, so a row that arrived from another station or from an N1MM
+        // database keeps what it was given
+        if (IsWorked(qso) || qso.ContactType.Equals("D", StringComparison.OrdinalIgnoreCase))
+        {
+            return "D";
+        }
+        // N1MM adds our own callsign to whatever the contest says
+        bool workable = contest.IsWorkable(ContextFor(qso))
+                        && !qso.Call.Text.Equals(me.Callsign, StringComparison.OrdinalIgnoreCase);
+        return workable ? "" : "N";
+    }
 
     private static Qso ApplyMultiplierFlags(Qso qso, IReadOnlyList<Multiplier> claimed) => qso with
     {