Add the YOTA and OK/OM DX contests

Both are in the station's log and neither could be opened. The rules are
written from the published ones and checked by replaying the log.

YOTA scores a contact by the age the other operator sends: 13 points down to 10
for anyone 25 or under, whatever the continent, and 1 point or 3 for everyone
else. Every age worked on a band is a multiplier. The 2024, 2025 and 2026 logs
come out to the contact.

OK/OM DX is the first contest whose exchange differs by the other station's
country: a county from OK and OM stations, a serial number from everyone else,
in the two columns N1MM keeps them in, and `SkipsField` walks the entry window
past the box that does not apply. Points depend on which side the operator is
on, and Czechia and Slovakia count as the two countries they are. The 2023 log
comes out to the contact.

The Cabrillo exchange now gets the entry, because YOTA sends an age that only
the contest setup knows.

Two differences are left in the log, both from the .udc files the operator
used: their YOTA file only lists ages 7 to 25, so a younger operator scored as
an adult, and one OK/OM log was made with the file for stations outside OK and
OM while signing an OM call.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RoGtneMQaz4M9w7Kk49AVD

tests/Nonemm.Contests.Tests/OkOmDxTests.cs

@@ -0,0 +1,75 @@
+using Nonemm.Contests.Rules;
+using Nonemm.Core;
+using Nonemm.Core.Country;
+
+namespace Nonemm.Contests.Tests;
+
+public class OkOmDxTests
+{
+    private static readonly Contest Ssb = new OkOmDx(ModeCategory.Phone);
+
+    private static ContestLog LogFor(StationInfo me) => new(Ssb, me, TestLog.CountryFile);
+
+    private static Qso FromOkOm(string call, string county, double kilohertz = 14_025) =>
+        TestLog.Contact(call, kilohertz, mode: Modes.Usb, section: county);
+
+    private static Qso FromDx(string call, string number, double kilohertz = 14_025) =>
+        TestLog.Contact(call, kilohertz, mode: Modes.Usb, exchange: number);
+
+    [Theory]
+    [InlineData("OM3XYZ", 2)]
+    [InlineData("OK1XYZ", 3)]
+    public void AtHomeCzechiaAndSlovakiaAreTwoCountries(string call, int expected) =>
+        Assert.Equal(expected, LogFor(TestLog.Slovakia).Judge(FromOkOm(call, "NOV")).Points);
+
+    [Theory]
+    [InlineData("IK2XYZ", 3)]
+    [InlineData("JA1XYZ", 5)]
+    public void TheRestOfTheWorldIsScoredByContinent(string call, int expected) =>
+        Assert.Equal(expected, LogFor(TestLog.Slovakia).Judge(FromDx(call, "014")).Points);
+
+    [Theory]
+    [InlineData("OM3XYZ", 10)]
+    [InlineData("DL9XYZ", 1)]
+    [InlineData("IK2XYZ", 3)]
+    [InlineData("JA1XYZ", 5)]
+    public void AStationOutsideScoresTenForAnOkOmContact(string call, int expected) =>
+        Assert.Equal(expected, LogFor(TestLog.Germany).Judge(FromOkOm(call, "NOV")).Points);
+
+    [Fact]
+    public void CountriesAndCountiesBothCountOncePerBand()
+    {
+        ContestLog log = LogFor(TestLog.Slovakia);
+        Assert.Equal(
+            [1, 2],
+            log.Judge(FromOkOm("OM3XYZ", "NOV")).NewMultipliers.Select(m => m.Index).ToList());
+        log.Add(FromOkOm("OM3XYZ", "NOV"));
+        Assert.Empty(log.Judge(FromOkOm("OM4XYZ", "NOV")).NewMultipliers);
+        Assert.Single(log.Judge(FromOkOm("OM4XYZ", "PAR")).NewMultipliers);
+    }
+
+    [Fact]
+    public void AStationOutsideOkOmBringsItsCountryAndNoCounty() =>
+        Assert.Equal(
+            [1],
+            LogFor(TestLog.Slovakia).Judge(FromDx("IK2XYZ", "014")).NewMultipliers
+                .Select(m => m.Index)
+                .ToList());
+
+    /// The entry window walks the county box for an OK or OM station and the
+    /// serial box for everyone else.
+    [Fact]
+    public void OnlyOneOfTheTwoBoxesIsWalked()
+    {
+        IReadOnlyList<ExchangeField> fields = Ssb.ExchangeFieldsFor(TestLog.Slovakia);
+        CountryLookup? okom = TestLog.CountryFile.Find("OM3XYZ");
+        CountryLookup? dx = TestLog.CountryFile.Find("IK2XYZ");
+
+        Assert.Equal(
+            [ExchangeSlot.ReceivedReport, ExchangeSlot.Exchange1],
+            fields.Where(f => !Ssb.SkipsField(f, dx)).Select(f => f.Slot).ToList());
+        Assert.Equal(
+            [ExchangeSlot.ReceivedReport, ExchangeSlot.Section],
+            fields.Where(f => !Ssb.SkipsField(f, okom)).Select(f => f.Slot).ToList());
+    }
+}