fix(sat,rda): the dropdown reads the live list, and the RDA buttons answer

SATELLITES: the field read the list once, when the details panel first
mounted — which is at startup. A list saved in Preferences afterwards
therefore did nothing until a restart. It comes from App now, which
already reloads the lists when Preferences close.

RDA COMPARE: a failed comparison wrote its error into the message beside
the FILL DISTRICTS button, a row above — the error appeared under a
button nobody had pressed while the one that had been pressed showed
nothing, which reads as 'the button does nothing'. It has its own message
now, and reports the two results that look like silence: no disagreement
at all, and no Russian contacts to compare. Both buttons say what they
are doing while they do it, and the comparison logs before it starts
reading — on a remote MySQL that read is seconds of quiet.

rdacompare.go

@@ -80,8 +80,13 @@ func (a *App) CompareRDASources() (RDACompareResult, error) {
 	if a.qso == nil {
 		return res, fmt.Errorf("db not initialized")
 	}
+	// Said before the work starts, not only after: this reads the WHOLE log, and
+	// on a remote MySQL that is seconds of silence during which the only
+	// evidence that anything is happening is this line.
+	applog.Printf("rda compare: reading the log…")
 	rows, err := a.qso.List(a.ctx, qso.ListFilter{Limit: 1_000_000})
 	if err != nil {
+		applog.Printf("rda compare: reading the log failed: %v", err)
 		return res, err
 	}
 	for i := range rows {