fix: who's-on-air freq/appearance lag — prompt publish on activity + 5s widget poll

publishLiveStatus only ran on QSO log or the 15s heartbeat, and the widget polled
every 15s, so an operator's band/freq (and their appearance) could trail by up to
a minute. Now ReportLiveActivity debounce-publishes ~1.5s after a freq/band/mode
change, and the widget polls every 5s (and 1.5s after qso:logged).

livestatus.go

@@ -159,10 +159,23 @@ func (a *App) liveStatusOperator() (op, station string) {
 // ReportLiveActivity is called by the UI with the current entry-strip freq/band/
 // mode, used as a fallback for live status when the CAT isn't connected.
 func (a *App) ReportLiveActivity(freqHz int64, band, mode string) {
+	nb := strings.ToUpper(strings.TrimSpace(band))
+	nm := strings.ToUpper(strings.TrimSpace(mode))
 	a.liveActMu.Lock()
+	changed := a.liveFreqHz != freqHz || a.liveBand != nb || a.liveMode != nm
 	a.liveFreqHz = freqHz
-	a.liveBand = strings.ToUpper(strings.TrimSpace(band))
-	a.liveMode = strings.ToUpper(strings.TrimSpace(mode))
+	a.liveBand = nb
+	a.liveMode = nm
+	// Push a fresh row PROMPTLY when the operator's freq/band/mode changes, instead
+	// of waiting for the next 15 s heartbeat — otherwise "who's on air" showed a
+	// stale band and took up to a minute to catch up. Debounced so spinning the VFO
+	// doesn't hammer the shared MySQL.
+	if changed {
+		if a.livePublishTimer != nil {
+			a.livePublishTimer.Stop()
+		}
+		a.livePublishTimer = time.AfterFunc(1500*time.Millisecond, func() { a.publishLiveStatus() })
+	}
 	a.liveActMu.Unlock()
 }