fix(adif): CNTY must be STATE,COUNTY

ADIF defines CNTY as "STATE,COUNTY" — "GA,BARROW". OpsLog wrote the bare county
name, which a receiving logger cannot resolve: county names repeat across
states, and there is a Washington County in thirty of them. The award engine
here was never affected, since it reads the columns rather than the ADIF; the
damage was to every file we hand to someone else.

One writer covers everything — writeRecord — so this fixes file exports and the
LoTW, Club Log, HRDLog and QRZ uploads together. MY_CNTY gets the same
treatment.

The county alone is still written when no state is known: a bare name is worth
more than nothing, and inventing a prefix would be worse than either. A value
that already carries a comma passes through untouched, so re-exporting an
imported record cannot double the prefix.

Import is the mirror: "GA,BARROW" fills both columns, and a file carrying the
bare county — as OpsLog's own older exports do — still imports unchanged. The
state parsed out of CNTY only fills a blank STATE, never overrides it: STATE is
the dedicated field and the more specific statement.

internal/adif/roundtrip_test.go

@@ -20,7 +20,7 @@ func TestPromotedFieldsRoundTrip(t *testing.T) {
 	in := qso.QSO{
 		Callsign: "EA8ABC", Band: "20m", Mode: "SSB",
 		QSODate: time.Date(2026, 6, 6, 12, 0, 0, 0, time.UTC),
-		SIG: "POTA", SIGInfo: "US-0001", MySIG: "WWFF", MySIGInfo: "ONFF-0001",
+		SIG:     "POTA", SIGInfo: "US-0001", MySIG: "WWFF", MySIGInfo: "ONFF-0001",
 		WWFFRef: "ONFF-0001", MyWWFFRef: "F-FFF-0001",
 		Distance: &dist, RXPower: &rxp, AIndex: &a,
 		SKCC: "12345S", FISTS: "999", TenTen: "55555",