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.Contests/Rules/Arrl10Metre.cs

@@ -17,19 +17,29 @@ public sealed class Arrl10Metre : Contest
 
     public string CabrilloName => "ARRL-10";
 
-    public IReadOnlyList<ExchangeField> ExchangeFieldsFor(StationInfo me) =>
-    [
-        new ExchangeField("RST", ExchangeSlot.ReceivedReport, ExchangeFieldKind.Report),
-        new ExchangeField("S/P", ExchangeSlot.Section, ExchangeFieldKind.UsStateOrCanadianProvince),
-        new ExchangeField("Nr", ExchangeSlot.Exchange1, ExchangeFieldKind.Number),
-    ];
+    /// One box takes the state, province or serial number the other station
+    /// sends, as N1MM has it. The sent serial box is there only where this
+    /// station sends a number rather than a state.
+    public IReadOnlyList<ExchangeField> ExchangeFieldsFor(StationInfo me) => SendsState(me.CountryPrefix)
+        ?
+        [
+            new ExchangeField("Snt", ExchangeSlot.SentReport, ExchangeFieldKind.Report, IsRequired: false),
+            new ExchangeField("Rcv", ExchangeSlot.ReceivedReport, ExchangeFieldKind.Report),
+            new ExchangeField("Exch", ExchangeSlot.Exchange1, ExchangeFieldKind.Text) { Width = 6 },
+        ]
+        :
+        [
+            new ExchangeField("Snt", ExchangeSlot.SentReport, ExchangeFieldKind.Report, IsRequired: false),
+            new ExchangeField("SentNR", ExchangeSlot.SentNumber, ExchangeFieldKind.Number, IsRequired: false),
+            new ExchangeField("Rcv", ExchangeSlot.ReceivedReport, ExchangeFieldKind.Report),
+            new ExchangeField("Exch", ExchangeSlot.Exchange1, ExchangeFieldKind.Text) { Width = 6 },
+        ];
 
-    public bool SkipsField(ExchangeField field, CountryLookup? their) => field.Slot switch
-    {
-        ExchangeSlot.Section => their is not null && !SendsState(their.Entity.PrimaryPrefix),
-        ExchangeSlot.Exchange1 => their is not null && SendsState(their.Entity.PrimaryPrefix),
-        _ => false,
-    };
+    /// A number is a serial and anything else is a state or province.
+    public Qso FromExchange1(Qso qso, string typed) =>
+        int.TryParse(typed, out int number)
+            ? qso with { ReceivedNumber = number, Section = "" }
+            : qso with { ReceivedNumber = 0, Section = typed.Trim().ToUpperInvariant() };
 
     public IReadOnlyList<string> MultiplierNames => ["States", "Countries"];