fix(sat,decodes): the left column holds position too, and drift stops lying

Two things.

The sky plot and the position share the left column now, and the button
that opens it says so the way the right one does — it was a radar icon,
left over from when it toggled a plot inside the readout column, and the
gesture is the same one on both sides. The plot and the numbers are the
same answer at two precisions: azimuth and elevation drawn, then written
out to the digit. Having them at opposite ends of the window meant
reading a bearing off one side and finding it on the other.

And the band-drift warning, reported by W4TE. It compared the decoder's
announced band against RigState.Band, which is the TRANSMIT band — so
with slice A on 20 m running its own WSJT-X, slice B on 40 m, and
transmit focus on B, the 20 m decoder was told the rig was on 40 m while
the slice it listens to had been on 20 m throughout. The panel's own
comment had accepted this as a line that setup could read past; it is
worse than that, because the warning names a band and asserts something
false about the radio.

RigState now carries RxBands: every band the rig has a receiver on. One
entry on a single-VFO rig, one per slice on a Flex, the transmit band
always included so it cannot come back empty while the rig is on a
frequency. The warning fires only when the decoder announces a band
NOTHING on the radio is on, which is what it was always for and what a
lost CAT link actually looks like.

frontend/src/components/DecodesPanel.tsx

@@ -102,6 +102,9 @@ interface Props {
   // The band the RIG is on, when CAT is connected. Only ever compared with what
   // the decoder announces — see the drift warning.
   rigBand?: string;
+  // Every band the radio has a receiver on. A Flex running two slices has
+  // two, and a decoder on either of them is not drifting.
+  rigBands?: string[];
   onCall: (d: Decode) => void;
   // A single click: take the station without transmitting — fill the entry, and
   // point the panels at it. Absent, a click falls back to onCall.
@@ -641,7 +644,7 @@ function buildPeriods(filtered: Decode[], txMsgs: TxMsg[]) {
     }));
 }
 
-export function DecodesPanel({ decodes, txMsgs, txState, txStates, spotStatus, rigBand, onCall, onSelect, myCall, myGrid, onClear, onHalt, autoCallOn, onToggleAutoCall, autoCall, autoCallOnly, onSetAutoCallOnly, watchlist }: Props) {
+export function DecodesPanel({ decodes, txMsgs, txState, txStates, spotStatus, rigBand, rigBands, onCall, onSelect, myCall, myGrid, onClear, onHalt, autoCallOn, onToggleAutoCall, autoCall, autoCallOnly, onSetAutoCallOnly, watchlist }: Props) {
   const { t } = useI18n();
   // Column widths, dragged in the header and shared by every row. Persisted
   // through writeUiPref (not raw localStorage) so the layout travels with data/
@@ -778,9 +781,19 @@ export function DecodesPanel({ decodes, txMsgs, txState, txStates, spotStatus, r
   // Said, not decided. Using the rig's band instead would be wrong for anyone
   // decoding a second receiver on another band, and a warning costs that setup
   // nothing but a line it can read past.
+  //
+  // Compared against every band the radio is RECEIVING on, not the transmit
+  // band. Two slices on two bands with a decoder on each is a normal setup,
+  // and it made this warning lie: with slice A on 20 m, slice B on 40 m and
+  // transmit focus on B, the 20 m decoder was told the rig was on 40 m while
+  // the slice it listens to was on 20 m all along. The warning is for a
+  // decoder announcing a band NOTHING on the radio is on, which is what a
+  // lost CAT link actually looks like.
   const decoderBand = decodes.length ? (decodes[decodes.length - 1].band ?? '') : '';
-  const bandDrift = !!rigBand && !!decoderBand
-    && rigBand.toLowerCase() !== decoderBand.toLowerCase();
+  const onAir = (rigBands && rigBands.length ? rigBands : (rigBand ? [rigBand] : []))
+    .map((b) => b.toLowerCase());
+  const bandDrift = onAir.length > 0 && !!decoderBand
+    && !onAir.includes(decoderBand.toLowerCase());
   const driftInstance = decodes.length ? (decodes[decodes.length - 1].instance ?? '') : '';
 
   const liveMode = decodes.length ? decodes[decodes.length - 1].mode : txState?.mode;