feat(worked): fold portable callsigns into the worked-before history

Typing RK3DWA found nothing while RK3DWA/3 found 21 QSOs, so a station's
history was only visible if you happened to type the exact form it had been
logged under — and an operator who worked it as /0, /P or /MM saw none of it.
The other RDA tools and Log4OM fold these together; this does too.

The predicate strips the suffix from what was typed and matches "call = base OR
call LIKE base/%", so it works from either end: the base call finds the portable
QSOs and a portable call finds the plain ones. Deliberately not a bare prefix
LIKE 'RK3DWA%', which would also match RK3DWAB — a different station. The '/' is
what makes it the same operator.

Settings -> General to turn it off. Default ON, hence the inverted storage: an
existing install has no key, and reading that as OFF would leave everyone with
the behaviour we were asked to change.

Contest dupe checking is untouched — it runs through ContestDupe, a separate
binding, and stays an exact match as a contest requires.

frontend/src/lib/i18n.tsx

@@ -186,6 +186,7 @@ const en: Dict = {
   // General panel
   'gen.hint': 'App behaviour (saved instantly).',
   'gen.autofocusWB': 'Auto-focus "Worked before" for known stations',
+  'gen.workedVariants': '"Worked before" folds portable callsigns together', 'gen.workedVariantsHint': '(RK3DWA also finds RK3DWA/3, /P, /MM — and the other way round. Contest dupe checking stays exact.)',
   'gen.showBeam': 'Show the antenna beam heading on the Main map',
   'gen.startEqEnd': 'QSO start time = end time', 'gen.startEqEndHint': '(matches LoTW when you call a while)',
   'gen.showQsoRate': 'Show QSO rate in the header', 'gen.showQsoRateHint': '(QSOs/hour, projected from the last 10 / 60 min)',
@@ -607,6 +608,7 @@ const fr: Dict = {
   'relayauto.from': 'de', 'relayauto.to': 'à',
   'gen.hint': 'Comportement de l\'application (enregistré immédiatement).',
   'gen.autofocusWB': 'Focus auto sur « Déjà contacté » pour les stations connues',
+  'gen.workedVariants': '« Déjà contacté » regroupe les indicatifs portables', 'gen.workedVariantsHint': '(RK3DWA trouve aussi RK3DWA/3, /P, /MM — et inversement. Le contrôle de doublon en concours reste strict.)',
   'gen.showBeam': 'Afficher le cap de l\'antenne sur la carte principale',
   'gen.startEqEnd': 'Heure de début du QSO = heure de fin', 'gen.startEqEndHint': '(correspond à LoTW quand tu appelles un moment)',
   'gen.showQsoRate': 'Afficher le rythme QSO dans la barre du haut', 'gen.showQsoRateHint': '(QSO/heure, projeté sur les 10 / 60 dernières min)',