feat: re-check for updates when opening Help - About (no more stale 'up to date')

Opening About now fires a fresh CheckForUpdate with a 'Checking…' state, and
clears the update banner when the latest check finds nothing — so it reflects
reality instead of the last periodic check.

frontend/src/App.tsx

@@ -1155,6 +1155,15 @@ export default function App() {
   }, []);
   const [showDuplicates, setShowDuplicates] = useState(false);
   const [updateInfo, setUpdateInfo] = useState<{ latest: string; url: string; downloadUrl: string } | null>(null);
+  const [checkingUpdate, setCheckingUpdate] = useState(false);
+  // Fresh update check on demand (opening About), so it never shows a stale
+  // "you're up to date". Clears updateInfo when the latest check finds nothing.
+  const checkUpdateNow = useCallback(() => {
+    setCheckingUpdate(true);
+    CheckForUpdate().then((u: any) => {
+      setUpdateInfo(u?.available && u?.latest ? { latest: String(u.latest), url: String(u.url ?? ''), downloadUrl: String(u.download_url ?? '') } : null);
+    }).catch(() => {}).finally(() => setCheckingUpdate(false));
+  }, []);
   const [updating, setUpdating] = useState(false);
   const [updateProgress, setUpdateProgress] = useState(0);
   const [updateError, setUpdateError] = useState('');
@@ -2831,7 +2840,7 @@ export default function App() {
       case 'tools.duplicates':  setShowDuplicates(true); break;
       case 'tools.refreshCty':  refreshCtyDat(); break;
       case 'tools.downloadRefs': downloadRefs(); break;
-      case 'help.about':        setShowAbout(true); break;
+      case 'help.about':        setShowAbout(true); checkUpdateNow(); break;
       case 'help.whatsnew':     GetChangelog().then((e: any) => { if (Array.isArray(e) && e.length) setWhatsNew(e); else showToast(t('whatsnew.none')); }).catch(() => {}); break;
     }
   }
@@ -4122,12 +4131,14 @@ export default function App() {
             </div>
             <p className="text-sm text-muted-foreground">Ham-radio logbook</p>
             <p className="mt-3 font-mono text-sm">version <span className="font-semibold text-foreground">{APP_VERSION}</span></p>
-            {updateInfo ? (
+            {checkingUpdate ? (
+              <p className="mt-1 text-[11px] text-muted-foreground inline-flex items-center gap-1"><Loader2 className="size-3 animate-spin" /> {t('upd.checking')}</p>
+            ) : updateInfo ? (
               <button onClick={() => updateInfo.url && BrowserOpenURL(updateInfo.url)} className="mt-1 text-xs text-primary underline hover:opacity-80">
                 Update available: v{updateInfo.latest} — download
               </button>
             ) : (
-              <p className="mt-1 text-[11px] text-success">You're up to date</p>
+              <p className="mt-1 text-[11px] text-success">{t('upd.upToDate')}</p>
             )}
             <p className="mt-3 text-sm">
               Developed by <span className="font-semibold text-primary">{APP_AUTHOR}</span>

frontend/src/lib/i18n.tsx

@@ -22,7 +22,7 @@ const en: Dict = {
   'upd.install': 'Update now', 'upd.download': 'Download', 'upd.later': 'Later',
   'upd.downloading': 'Downloading…', 'upd.installing': 'Installing…',
   'upd.restartNote': 'OpsLog will restart on the new version.',
-  'upd.retry': 'Retry', 'upd.browser': 'Open page',
+  'upd.retry': 'Retry', 'upd.browser': 'Open page', 'upd.checking': 'Checking for updates…', 'upd.upToDate': "You're up to date",
   'rate.title': 'QSO rate (QSOs/hour) — projected from the last 10 / 60 minutes',
   'lotw.userTip': 'LoTW user — last upload {date} ({days} days ago)',
   'menu.file': 'File', 'menu.edit': 'Edit', 'menu.view': 'View', 'menu.tools': 'Tools',
@@ -369,6 +369,7 @@ const fr: Dict = {
   'btn.logQso': 'Enregistrer', 'btn.clear': 'Effacer', 'btn.spot': 'Spot', 'btn.saving': '…',
   'lang.choose': 'Choisissez votre langue', 'lang.chooseHint': 'Modifiable plus tard dans Réglages → Général.',
   'lang.english': 'English', 'lang.french': 'Français', 'whatsnew.title': 'Nouveautés', 'whatsnew.close': 'Compris', 'whatsnew.none': 'Aucune nouveauté pour cette version pour le moment.',
+  'upd.checking': 'Recherche de mises à jour…', 'upd.upToDate': 'Vous êtes à jour',
   'settings.language': 'Langue', 'settings.languageHint': "Langue de l'interface.",
   'stats.tab': 'Statistiques', 'stats.title': 'Statistiques du journal', 'stats.loading': 'Analyse du journal…',
   'stats.noData': 'Aucune donnée', 'stats.charts': 'Graphiques', 'stats.table': 'Tableau', 'stats.refresh': 'Rafraîchir',