feat(bandmap): mark LoTW users, with the badge the cluster already uses

Logger32 draws a green square for a LoTW user and an X for a worked one. The
square is the part worth copying; the way it is drawn is not.

Colour on this map is already spoken for — it carries the entity status, and
the left edge of each pill stacks the new-park / new-county markers. Adding a
green fill for LoTW would put two unrelated meanings on one channel, and an
operator would have to work out which green meant what. So it is the same "L"
badge the cluster list draws, in the same muted blue, for the reason written
there: whether a station uploads to LoTW says nothing about whether the spot is
worth chasing.

Worked stations already read as worked here — the pill goes grey and the
status markers speak — so no X is needed.

Switchable in Settings → Appearance, and on by default: a `configured` flag
distinguishes "saved with this off" from "saved before the option existed", so
turning it off sticks instead of being undone by the next default.

frontend/src/App.tsx

@@ -6800,6 +6800,7 @@ export default function App() {
                       onClose={() => toggleBandMapBand(b)}
                       hideDigital={bandMapHideFt}
                       fitToBand={bandMapFit}
+                      showLotw={!!rowColors?.bandmap_lotw}
                     />
                   </div>
                 ))}