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/county_test.go

@@ -0,0 +1,46 @@
+package adif
+
+import "testing"
+
+// ADIF defines CNTY as "STATE,COUNTY" — "GA,BARROW". OpsLog exported the bare
+// county, which a receiving logger cannot resolve: county names repeat across
+// states, and there is a Washington County in thirty of them.
+func TestADIFCountyFormat(t *testing.T) {
+	for _, tc := range []struct{ state, county, want string }{
+		{"GA", "BARROW", "GA,BARROW"},
+		{"ga", "Barrow", "GA,Barrow"},    // the state is a code, upper-cased; the name is not touched
+		{"", "BARROW", "BARROW"},         // no state known: a bare name beats nothing
+		{"GA", "", ""},                   // no county: nothing to write
+		{"GA", "GA,BARROW", "GA,BARROW"}, // already formatted — never double the prefix
+		{"  GA  ", " BARROW ", "GA,BARROW"},
+	} {
+		if got := adifCounty(tc.state, tc.county); got != tc.want {
+			t.Errorf("adifCounty(%q, %q) = %q, want %q", tc.state, tc.county, got, tc.want)
+		}
+	}
+}
+
+// And the mirror: a file from a logger that follows the standard must fill both
+// columns, while a file carrying the bare county still imports unchanged.
+func TestSplitADIFCounty(t *testing.T) {
+	for _, tc := range []struct{ in, county, state string }{
+		{"GA,BARROW", "BARROW", "GA"},
+		{"ga, Barrow", "Barrow", "GA"},
+		{"BARROW", "BARROW", ""}, // the old OpsLog form, and many other loggers
+		{"", "", ""},
+		{"  ", "", ""},
+	} {
+		c, s := splitADIFCounty(tc.in)
+		if c != tc.county || s != tc.state {
+			t.Errorf("splitADIFCounty(%q) = (%q, %q), want (%q, %q)", tc.in, c, s, tc.county, tc.state)
+		}
+	}
+}
+
+// Round trip: what OpsLog writes, OpsLog reads back to the same two values.
+func TestCountyRoundTrip(t *testing.T) {
+	c, s := splitADIFCounty(adifCounty("GA", "BARROW"))
+	if c != "BARROW" || s != "GA" {
+		t.Errorf("round trip gave (%q, %q), want (BARROW, GA)", c, s)
+	}
+}