feat: New tool to remove duplicates in the log

frontend/src/App.tsx

@@ -70,6 +70,7 @@ import { cleanSpotter, inferSpotMode, spotModeCategory, spotStatusKey } from '@/
 import { WorkedBeforeGrid } from '@/components/WorkedBeforeGrid';
 import { NetControlPanel } from '@/components/NetControlPanel';
 import { ContestPanel, CONTEST_DEFAULT, type ContestSession } from '@/components/ContestPanel';
+import { DuplicatesModal } from '@/components/DuplicatesModal';
 import { useI18n } from '@/lib/i18n';
 import { AlertsModal } from '@/components/AlertsModal';
 import { BulkEditModal } from '@/components/BulkEditModal';
@@ -907,6 +908,7 @@ export default function App() {
   const [settingsSection, setSettingsSection] = useState<string | undefined>(undefined);
   const [showDeleteAll, setShowDeleteAll] = useState(false);
   const [showAbout, setShowAbout] = useState(false);
+  const [showDuplicates, setShowDuplicates] = useState(false);
   const [updateInfo, setUpdateInfo] = useState<{ latest: string; url: string } | null>(null);
   // Check GitHub for a newer release once at startup (unless disabled in
   // General); surface a toast if one exists. Best effort — silent on failure.
@@ -2325,6 +2327,8 @@ export default function App() {
       { type: 'item', label: (netEnabled ? '✓ ' : '') + t('tools.net'), action: 'tools.net' },
       { type: 'item', label: t('tools.alerts'), action: 'tools.alerts' },
       { type: 'separator' },
+      { type: 'item', label: t('tools.duplicates'), action: 'tools.duplicates', disabled: total === 0 },
+      { type: 'separator' },
       // Maintenance — bumped here while we only have one entry. Will move
       // to a Tools → Maintenance submenu once Clublog + LoTW refresh land.
       { type: 'item', label: ctyRefreshing ? 'Refreshing cty.dat…' : 'Refresh cty.dat', action: 'tools.refreshCty', disabled: ctyRefreshing },
@@ -2354,6 +2358,7 @@ export default function App() {
       case 'tools.cwdecoder':   toggleCwDecoder(); break;
       case 'tools.net':         setNetEnabled((v) => { const nv = !v; if (nv) setActiveTab('net'); return nv; }); break;
       case 'tools.alerts':      setAlertsOpen(true); break;
+      case 'tools.duplicates':  setShowDuplicates(true); break;
       case 'tools.refreshCty':  refreshCtyDat(); break;
       case 'tools.downloadRefs': downloadRefs(); break;
       case 'help.about':        setShowAbout(true); break;
@@ -4251,6 +4256,10 @@ export default function App() {
         <AlertsModal onClose={() => setAlertsOpen(false)} bands={bands} modes={modes} countries={countries} />
       )}
 
+      {showDuplicates && (
+        <DuplicatesModal onClose={() => setShowDuplicates(false)} onDeleted={() => refresh()} />
+      )}
+
       <AutoEQSL
         onSent={(call) => showToast(`OpsLog QSL sent to ${call}`)}
         onError={(msg) => showToast(msg)}