feat(awards): find the slots worked but not confirmed

The Challenge line says 1832 worked against 1554 confirmed and stops there —
278 band-slots waiting for a card with nothing pointing at them. Every existing
filter works per REFERENCE, so an entity confirmed on 20 m answers 'confirmed'
and its unconfirmed 15 m contact stays invisible.

The new filter keeps the references holding at least one such slot, and the
count beside the reference total is the gap itself, recomputed over whatever the
other filters left on screen and over the bands actually displayed — so it
always adds up to the columns in front of the operator.

frontend/src/lib/i18n.tsx

@@ -128,6 +128,8 @@ const en: Dict = {
   'mx.tipDxConf': 'Entity confirmed (other callsign)', 'mx.tipDxWork': 'Entity worked (other callsign)',
   'mx.tipNone': 'Never worked', 'mx.tipClick': 'click to list the QSOs',
   'icmp.scopeNoStream': 'This radio does not send its scope over CI-V — its own screen still works.',
+  'awp.filterSlotsNotCfmd': 'Slots to confirm', 'awp.slotGap': 'slots to confirm',
+  'awp.slotGapTip': 'Band-slots worked and not yet confirmed — the difference between the worked and confirmed totals above.',
   'mx.markWork': 'This callsign worked', 'mx.markConf': 'This callsign confirmed',
   'mx.tipThisCall': 'already worked with this callsign',
   'mx.tipThisCallConf': 'already confirmed with this callsign',
@@ -618,6 +620,8 @@ const fr: Dict = {
   'mx.tipDxConf': 'Entité confirmée (autre indicatif)', 'mx.tipDxWork': 'Entité contactée (autre indicatif)',
   'mx.tipNone': 'Jamais contacté', 'mx.tipClick': 'cliquer pour lister les QSO',
   'icmp.scopeNoStream': "Cette radio n'envoie pas son scope en CI-V — son propre écran fonctionne toujours.",
+  'awp.filterSlotsNotCfmd': 'Slots à confirmer', 'awp.slotGap': 'slots à confirmer',
+  'awp.slotGapTip': "Créneaux bande contactés et pas encore confirmés — l'écart entre les totaux contactés et confirmés ci-dessus.",
   'mx.markWork': 'Cet indicatif contacté', 'mx.markConf': 'Cet indicatif confirmé',
   'mx.tipThisCall': 'déjà contacté avec cet indicatif',
   'mx.tipThisCallConf': 'déjà confirmé avec cet indicatif',