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/lib/i18n.tsx

@@ -39,7 +39,7 @@ const en: Dict = {
   'cwd.tipOnIdle': 'CW decoder — on, idle until CW mode · click to disable',
   'cwd.tipOff': 'CW decoder · click to enable (decodes RX audio in CW mode)',
   'tools.watchlist': 'Watchlist…', 'tab.watchlist': 'Watchlist',
-  'wl.addPh': 'Callsign or prefix', 'wl.add': 'Add', 'wl.contest': 'Contest',
+  'wl.addPh': 'Callsign or prefix', 'wl.add': 'Add', 'wl.contest': 'Contest', 'wl.addAsContest': 'as contest',
   'wl.contestHint': 'Contest station: worked/needed is judged against the current UTC day — at 00:00 UTC every slot can be worked again.',
   'wl.searchPh': 'Search…', 'wl.famAll': 'All', 'wl.famNormal': 'DX', 'wl.famContest': 'Contest',
   'wl.activeOnly': 'Active only', 'wl.neededOnly': 'Needed only',
@@ -122,7 +122,7 @@ const en: Dict = {
   'settings.leftPane': 'Left pane', 'settings.thirdPane': 'Third pane', 'settings.fourthPane': 'Fourth pane', 'settings.paneNone': '— none —', 'settings.paneLayout': 'With four panes:', 'settings.paneQuad': 'Quarters (2 × 2)', 'settings.paneCols': 'Four columns', 'settings.rightPane': 'Right pane',
   'settings.pane.map1': 'Map — great-circle + beam', 'settings.pane.map2': 'Map — locator (street)',
   'settings.pane.cluster': 'Cluster spots', 'settings.pane.worked': 'Worked before',
-  'settings.pane.recent': 'Recent QSOs', 'settings.pane.netcontrol': 'Net control', 'settings.pane.decodes': 'FT decodes',
+  'settings.pane.recent': 'Recent QSOs', 'settings.pane.netcontrol': 'Net control', 'settings.pane.decodes': 'FT decodes', 'settings.pane.watchlist': 'Watchlist',
   'settings.pane.flex': 'Flex Console', 'tcip.console': "SunSDR Console", 'settings.pane.tci': "SunSDR Console", 'settings.pane.elecraft': "Elecraft Console", 'tcip.waiting': "Waiting for the radio — TCI is not connected.", 'tcip.meters': "Meters", 'tcip.transmit': "Transmit", 'tcip.receive': "Receive", 'tcip.drive': "Drive", 'tcip.tuneDrive': "Tune drive", 'tcip.mic': "Mic gain", 'tcip.volume': "Volume", 'tcip.squelch': "Squelch", 'tcip.agc': "AGC", 'tcip.filter': "Filter", 'tcip.mute': "MUTE", 'tcip.lock': "LOCK", 'tcip.off': "off", 'tcip.tune': "TUNE", 'tcip.tuning': "TUNING", 'tcip.txDisabled': "The radio is not allowing transmit", 'tcip.sMeterHint': "Click to put this report in the entry form. The radio sends a real signal level in dBm, so the S units are arithmetic rather than a calibration guess.", 'settings.pane.icom': 'Icom Console', 'settings.pane.yaesu': 'Yaesu Console', 'yaesu.notConnected': 'Yaesu CAT not connected', 'yaesu.meters': 'Meters', 'yaesu.bandMode': 'Band & mode', 'yaesu.receive': 'Receive', 'yaesu.noiseFilter': 'Noise & filter', 'yaesu.transmit': 'Transmit', 'yaesu.refresh': 'Refresh', 'yaesu.narrowHint': 'Narrow IF filter (NAR) — tightens the receive bandwidth. Only shown when the radio answers the command.', 'yaesu.tuneHint': 'Start an antenna-tuner cycle', 'yaesu.sToRst': 'Click to fill the RST sent', 'yaesu.sidebandHint': 'Click to select this mode; click again to switch sideband (U/L)', 'yaesu.splitUpHint': 'Transmit this far above the receive frequency, and turn split on', 'yaesu.txOn': 'TX', 'yaesu.cw': 'CW', 'yaesu.breakInHint': 'Break-in: the rig switches to receive between characters', 'yaesu.zinHint': 'Zero-in: retune so the station you hear lands on your CW pitch',
   'theme.auto': 'Auto (system)', 'theme.light-warm': 'Warm light', 'theme.light-cool': 'Cool light',
   'theme.light-sage': 'Sage light', 'theme.light-nordic': 'Nordic light', 'theme.sahara': 'Sahara', 'theme.dim-slate': 'Dim slate', 'theme.dark-warm': 'Warm dark',
@@ -563,7 +563,7 @@ const fr: Dict = {
   'cwd.tipOnIdle': 'Décodeur CW — actif, en veille hors mode CW · clic pour désactiver',
   'cwd.tipOff': 'Décodeur CW · clic pour activer (décode l’audio RX en mode CW)',
   'tools.watchlist': 'Watchlist…', 'tab.watchlist': 'Watchlist',
-  'wl.addPh': 'Indicatif ou préfixe', 'wl.add': 'Ajouter', 'wl.contest': 'Contest',
+  'wl.addPh': 'Indicatif ou préfixe', 'wl.add': 'Ajouter', 'wl.contest': 'Contest', 'wl.addAsContest': 'comme contest',
   'wl.contestHint': "Station contest : contacté/manquant est jugé sur la journée UTC courante — à 00:00 UTC chaque créneau redevient à faire.",
   'wl.searchPh': 'Chercher…', 'wl.famAll': 'Tous', 'wl.famNormal': 'DX', 'wl.famContest': 'Contest',
   'wl.activeOnly': 'Actifs seulement', 'wl.neededOnly': 'Manquants seulement',