Show the boxes N1MM shows for each contest

The entry window had a fixed set of boxes with a Name and Comment box beside
the exchange. N1MM lays out one row of boxes per contest and nothing else, so
this does the same: general logging keeps Name and Comment, and a contest gets
the boxes it exchanges.

Two new members on `Contest` carry the cases where the boxes and the log
columns are not the same list:

- `FromExchange1` spreads what was typed in one box across the log columns.
  Where the other station sends a serial or a district code depending on where
  it is, N1MM gives it one box and sorts the value into the number, section or
  zone column from there, so the score and the Cabrillo file read it from the
  same column N1MM does.
- `LogFieldsFor` gives the log window its own column list. Sweepstakes takes
  the whole exchange in one box and logs it in four columns; `SweepstakesExchange`
  parses `72 A 74 SCV` in any order, reading from the last word back as N1MM
  does.

The sent serial is now marked as not required and space steps over it along
with the two report boxes, because nobody types the number going out.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015NZkFxHde1iifAQemFTHxf

src/Nonemm.Session/EntryFields.cs

@@ -65,9 +65,9 @@ public sealed class EntryFields
     public void FocusOn(int field) => Focus = Math.Clamp(field, 0, FieldCount - 1);
 
     /// What space and tab do: move to the next box the operator types in, and
-    /// round to the callsign again from the last one. The report boxes are
-    /// stepped over, because nobody types 599 — N1MM steps over them too, and
-    /// fills them in instead.
+    /// round to the callsign again from the last one. The report boxes and the
+    /// sent serial are stepped over, because nobody types 599 or the number
+    /// they are sending — N1MM steps over the same three and fills them in.
     public void Advance() => Focus = Next(1);
 
     public void Retreat() => Focus = Next(-1);
@@ -78,7 +78,7 @@ public sealed class EntryFields
         for (int step = 0; step < FieldCount; step++)
         {
             at = (at + by + FieldCount) % FieldCount;
-            if (at == 0 || Exchange[at - 1].Kind != ExchangeFieldKind.Report)
+            if (at == 0 || !IsFilledIn(Exchange[at - 1]))
             {
                 return at;
             }
@@ -86,6 +86,9 @@ public sealed class EntryFields
         return Focus;
     }
 
+    private static bool IsFilledIn(ExchangeField field) =>
+        field.IsSent || field.Kind == ExchangeFieldKind.Report;
+
     /// True when everything the contest asks for has been typed.
     public bool IsComplete =>
         Call.Trim().Length > 0 &&