feat: HAMLOG.online upload and confirmations, Yaesu antenna, a named port holder

HAMLOG.online is a seventh external service: one API key, one ADIF record per
QSO, immediate / delayed / on-close like the rest. They publish no API
documentation, so the protocol is read from THEIR OWN client — the HAMLOG Agent
(github.com/hamlogonline/Agent), which is the authoritative source short of
asking them:

	POST https://hamlog.online/api/agent/
	{"ADIFADD": {"APIKEY": k, "ADIFDATA": record}}   → {"STATUS":"OK"}
	{"KEYSTATUS": {"APIKEY": k}}                     → {"STATUS":"OK","CALLSIGN":…}

Success is STATUS == OK, not "no ERROR field": their failure carries ERROR and
no STATUS, and reading an unknown reply — a proxy page, a maintenance notice —
as an acceptance is how a contact goes missing without anyone noticing.

KEYSTATUS buys something no other service here offers: the key can be checked
BEFORE the first QSO, and the answer names the account. A key pasted from
another callsign is caught in the settings panel rather than through a week of
silent refusals.

Their confirmations are also an award source now, ticked like LoTW rather than
expressed through "custom". It reads the ADIF extras, not a column: the standard
names a field for hamlog.EU and none for hamlog.ONLINE, and borrowing the other
site's field would write a falsehood into every exported log. Three plausible
key names from their own export are accepted too, so nobody has to rename a
column by hand after an export.

Yaesu gains antenna selection (AN), remembered per band — the antenna picked on
a band comes back with it, with no table to fill in anywhere. Rigs with one
socket never answer AN and never show the row; the log says which case it is.

And a serial port that is refused now names its likely holder. OmniRig stays
resident once activated and keeps the port of the rig configured in it, so a
native backend never gets it — "Serial port busy" alone accused nobody, and an
FTDX10 spent a morning being blamed for it.

internal/cat/yaesu_test.go

@@ -1,6 +1,9 @@
 package cat
 
-import "testing"
+import (
+	"fmt"
+	"testing"
+)
 
 func TestParseYaesuFreq(t *testing.T) {
 	cases := []struct {
@@ -380,3 +383,26 @@ func TestYaesuModeVFOSuffix(t *testing.T) {
 		t.Errorf("setting CW on main sends %q, want MD03;", cmd)
 	}
 }
+
+// The antenna command, as the FTDX10 reference gives it: AN + receiver + jack.
+// The jack is clamped rather than trusted — a panel bug that sent AN09 would be
+// answered by the rig with silence, and the operator would be left wondering
+// which antenna they were on.
+func TestYaesuAntennaCommand(t *testing.T) {
+	for _, tc := range []struct {
+		in   int
+		want string
+	}{
+		{1, "AN01;"},
+		{2, "AN02;"},
+		{3, "AN03;"},
+		{0, "AN01;"}, // below range → the first jack
+		{9, "AN03;"}, // above range → the last
+		{-1, "AN01;"},
+	} {
+		got := fmt.Sprintf("AN0%d;", clampInt(tc.in, 1, 3))
+		if got != tc.want {
+			t.Errorf("antenna %d → %q, want %q", tc.in, got, tc.want)
+		}
+	}
+}