feat(watchlist): dockable in the Main tab; sticky filters; Needed-only hides worked lines

The watchlist joins the Main-tab pane list (Settings → Main view), rendered in
a card like the other docked panels.

The three filters persist across tab switches — the component unmounts on every
switch, and filters that reset each time are filters nobody trusts.

Needed-only now hides the worked SPOT LINES as well as the all-worked cards,
which is DXHunter's own Not-Worked behaviour and the reported complaint: a
filter that says needed and still lists five green Worked rows answers a
different question than the one asked.

The add-row checkbox is relabelled 'as contest' — it marks the entry being
ADDED, and read as a filter beside the All/DX/Contest buttons it looked
redundant.

frontend/src/components/WatchlistTab.tsx

@@ -52,9 +52,17 @@ export function WatchlistTab({ spots, spotStatus, onSpotSelect, onSpotClick }: P
   const [addCall, setAddCall] = useState('');
   const [addContest, setAddContest] = useState(false);
   const [search, setSearch] = useState('');
-  const [neededOnly, setNeededOnly] = useState(false);
-  const [activeOnly, setActiveOnly] = useState(false);
-  const [family, setFamily] = useState<'all' | 'normal' | 'contest'>('all');
+  // The filters survive leaving the tab: the component unmounts on every tab
+  // switch, and filters that reset each time are filters nobody trusts.
+  const [neededOnly, setNeededOnlyRaw] = useState(() => localStorage.getItem('opslog.wlNeededOnly') === '1');
+  const [activeOnly, setActiveOnlyRaw] = useState(() => localStorage.getItem('opslog.wlActiveOnly') === '1');
+  const [family, setFamilyRaw] = useState<'all' | 'normal' | 'contest'>(() => {
+    const v = localStorage.getItem('opslog.wlFamily');
+    return v === 'normal' || v === 'contest' ? v : 'all';
+  });
+  const setNeededOnly = (f: (v: boolean) => boolean) => setNeededOnlyRaw((v) => { const nv = f(v); try { localStorage.setItem('opslog.wlNeededOnly', nv ? '1' : '0'); } catch {} return nv; });
+  const setActiveOnly = (f: (v: boolean) => boolean) => setActiveOnlyRaw((v) => { const nv = f(v); try { localStorage.setItem('opslog.wlActiveOnly', nv ? '1' : '0'); } catch {} return nv; });
+  const setFamily = (v: 'all' | 'normal' | 'contest') => { setFamilyRaw(v); try { localStorage.setItem('opslog.wlFamily', v); } catch {} };
   const [error, setError] = useState('');
   const [removeArm, setRemoveArm] = useState('');
   // worked answer per "call|band|modeclass|contest" key.
@@ -178,7 +186,7 @@ export function WatchlistTab({ spots, spotStatus, onSpotSelect, onSpotClick }: P
           onKeyDown={(e) => { if (e.key === 'Enter') void add(); }} />
         <label className="flex items-center gap-1.5 text-xs cursor-pointer" title={t('wl.contestHint')}>
           <Checkbox checked={addContest} onCheckedChange={(c) => setAddContest(!!c)} />
-          <Trophy className="size-3.5 text-warning" /> {t('wl.contest')}
+          <Trophy className="size-3.5 text-warning" /> {t('wl.addAsContest')}
         </label>
         <Button size="sm" className="h-8" onClick={() => void add()} disabled={!addCall.trim()}>
           <Plus className="size-3.5" /> {t('wl.add')}
@@ -218,8 +226,12 @@ export function WatchlistTab({ spots, spotStatus, onSpotSelect, onSpotClick }: P
             {entries.length === 0 ? t('wl.empty') : t('wl.noneMatch')}
           </div>
         ) : shown.map((e) => {
-          const list = spotsFor.get(e.callsign) ?? [];
-          const needed = list.filter((s) => !workedFor(e, s)).length;
+          const all = spotsFor.get(e.callsign) ?? [];
+          const needed = all.filter((s) => !workedFor(e, s)).length;
+          // Needed-only hides the worked LINES as well as the all-worked cards:
+          // a filter that says needed and still lists five green Worked rows is
+          // answering a different question than the one asked.
+          const list = neededOnly ? all.filter((s) => !workedFor(e, s)) : all;
           return (
             <div key={e.callsign}
               className={cn('rounded-lg border bg-card p-3',