fix(antenna,udp): name the reason tracking is off; infer the remote-tune unit

The SteppIR report was not a SteppIR fault. In the log the antenna starts,
answers every poll, and sits at 21050 kHz while the rig works 21074 — and the
status line only prints when the frame CHANGES, so a link that is alive and
parked looks identical to one that died. The one line that explained it said
"ultrabeam: follow loop stopped", which covers two quite different situations
and, at startup where nothing was running, reads as a fault. Tracking was simply
switched off. It now says which of the two it is, names the antenna type, and
states the consequence — that the antenna will not follow the rig.

Same log, a second and unrelated fault: every launch failed a tune request from
DXHunter with "frequency 2107400000000 out of the 11-digit CAT range".
<FREQ> was read as MHz, but DXHunter had echoed back the value OpsLog itself
published in the N1MM RadioInfo broadcast, whose <Freq> is in tens of Hz. Both
units come from the same peer, so the unit is now inferred: try MHz, kHz, Hz,
tens of Hz, and keep the first that lands on an amateur band — anything a
station is asked to tune to is in one. Hz before tens of Hz because their only
overlap, 40 m against 4 m, is far more likely to be 40 m. Nothing plausible
tunes nothing and says so, rather than sending the rig to a wrong band.

app.go

@@ -15900,13 +15900,24 @@ func (a *App) restartMotorFollow(s UltrabeamSettings) {
 		close(a.ubFollowStop)
 		a.ubFollowStop = nil
 	}
-	if !s.Follow || a.motorAnt == nil {
-		applog.Printf("ultrabeam: follow loop stopped")
+	// Say WHICH of the two reasons it is. "follow loop stopped" covered both, and
+	// at startup — where nothing was running to stop — it read as a fault. An
+	// operator whose antenna sat at 21050 while the rig worked 21074 sent a log
+	// that said the antenna had started, answered every poll, and had its follow
+	// loop "stopped": three lines that together looked like a link going dead,
+	// when tracking was simply switched off and the antenna was waiting to be
+	// tuned by hand.
+	if a.motorAnt == nil {
+		applog.Printf("antenna: tracking not started — no antenna connected")
+		return
+	}
+	if !s.Follow {
+		applog.Printf("antenna: %s connected, but TRACKING IS OFF in Settings — it will not follow the rig, and only moves when you tune it by hand", s.Type)
 		return
 	}
 	stop := make(chan struct{})
 	a.ubFollowStop = stop
-	applog.Printf("ultrabeam: follow loop restarting — covered bands %v, mode %s, step %d kHz", s.Bands, normMotorTrackMode(s.TrackMode), s.StepKHz)
+	applog.Printf("antenna: %s tracking the rig — covered bands %v, mode %s, step %d kHz", s.Type, s.Bands, normMotorTrackMode(s.TrackMode), s.StepKHz)
 	go a.ultrabeamFollowLoop(a.motorAnt, s.TrackMode, s.StepKHz, s.Bands, stop)
 }