Name the All Asian multiplier after what it counts

The score window and the stored Contest.Multiplier1Name row both said
"Prefixes" for an Asian entrant, which counts DXCC entities.

Contest.MultiplierNames is now MultiplierNamesFor(StationInfo me), the
same shape as ExchangeFieldsFor. Every other contest returns the same
list it did before; All Asian returns "Countries" from Asia and
"Prefixes" from everywhere else. ContestDefinitions.For takes the
station as well, because that name is written to the log for N1MM.

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

src/Nonemm.Contests/Rules/FieldDayRegionOne.cs

@@ -21,7 +21,7 @@ public sealed class FieldDayRegionOne : Contest
         new ExchangeField("Nr", ExchangeSlot.SerialNumber, ExchangeFieldKind.Number),
     ];
 
-    public IReadOnlyList<string> MultiplierNames => ["Countries"];
+    public IReadOnlyList<string> MultiplierNamesFor(StationInfo me) => ["Countries"];
 
     public DupeScope DupeScope => DupeScope.PerBandAndMode;