feat(decodes): offer the panel as a Main-view pane

It joins the left/right dropdowns in Settings -> General alongside the maps,
the cluster and the rest, so decodes can sit beside the entry strip instead
of only behind a tab. Per-profile like the other pane choices.

The panel itself is now built in ONE place and rendered from both: two
copies of that call would be two sets of props to keep in step, and the
click handler in particular is not something to duplicate.

The status refresh follows. Its "is anything showing a spot status?" test
decides whether a logged QSO refreshes the NEW badges now or only marks
them dirty, and a panel that had become a pane would have gone on wearing
stale badges whenever it was shown that way rather than as a tab.

frontend/src/components/SettingsModal.tsx

@@ -1029,7 +1029,7 @@ function RelayAutoPanel() {
 // panes show, independently: the great-circle map, the locator street map, the
 // cluster grid or the worked-before grid. Per-profile (stored via SetUIPref,
 // which is profile-prefixed). Self-contained so it owns its async-loaded state.
-const MAIN_PANE_VALUES = ['map1', 'map2', 'cluster', 'worked', 'recent', 'netcontrol'];
+const MAIN_PANE_VALUES = ['map1', 'map2', 'cluster', 'worked', 'recent', 'netcontrol', 'decodes'];
 function MainViewPanes({ onChanged, flexAvailable, icomAvailable, yaesuAvailable }: { onChanged?: (side: 'left' | 'right', value: string) => void; flexAvailable?: boolean; icomAvailable?: boolean; yaesuAvailable?: boolean }) {
   const { t } = useI18n();
   const [left, setLeft] = useState('map1');