fix: bandmap opened or closed is now persistent over restart

frontend/src/App.tsx

@@ -685,7 +685,12 @@ export default function App() {
   }, []);
   // Single band map docked beside the table (toggled by the toolbar button,
   // visible across tabs). Independent of the multi-band "Band Map" tab.
-  const [showBandMap, setShowBandMap] = useState(false);
+  const [showBandMap, setShowBandMap] = useState(() => localStorage.getItem('bandmap.show') === '1');
+  // Persist the Band Map open/closed state (portable) so it survives a restart.
+  const setBandMapShown = useCallback((v: boolean) => {
+    setShowBandMap(v);
+    writeUiPref('bandmap.show', v ? '1' : '0');
+  }, []);
   const [bandMapSide, setBandMapSide] = useState<'left' | 'right'>(
     () => (localStorage.getItem('bandmap.side') === 'left' ? 'left' : 'right'),
   );
@@ -2879,7 +2884,7 @@ export default function App() {
             <Button
               variant={showBandMap ? 'default' : 'outline'}
               size="sm"
-              onClick={() => setShowBandMap((v) => !v)}
+              onClick={() => setBandMapShown(!showBandMap)}
               title="Toggle a single band map docked on the side (use the Band Map tab for several at once)"
               className="h-8"
             >
@@ -3642,7 +3647,7 @@ export default function App() {
               spotStatus={spotStatus}
               currentFreqHz={band && freqMhz ? Math.round(parseFloat(freqMhz) * 1_000_000) : 0}
               onSpotClick={handleSpotClick}
-              onClose={() => setShowBandMap(false)}
+              onClose={() => setBandMapShown(false)}
             />
           </div>
         )}