feat: account management overhaul + 7 issue resolutions (#147)

- Add smart JSON export/import with schema validation and deduplication
- Add per-account proxy configurations (Issue #79)
- Add advanced account sorting engine (Issues #126 & #99)
- Add compact horizontal layout, AI credits, inline model visibility (Issues #145 & #134)
- Add desktop push notifications for low quota (Issue #53)
- Fix Arch Linux AUR process detection bug (Issue #117)
- Default theme set to Dark Mode (it's better)
- UI Polishing: Improved sort dropdown and symmetrical dialog layouts
- Dev Mode: Resolved port conflicts and single-instance locks
- Updated README and README.zh-CN with new features

src/components/ProviderGroup.tsx

@@ -76,10 +76,12 @@ export const ProviderGroup: React.FC<ProviderGroupProps> = ({
             </span>
           )}
           <div className="flex items-baseline gap-1">
-            <span className={`font-mono text-xs font-bold ${getQuotaTextColorClass(avgPercentage)}`}>
+            <span
+              className={`font-mono text-xs font-bold ${getQuotaTextColorClass(avgPercentage)}`}
+            >
               {formatQuotaLabel(avgPercentage)}
             </span>
-            {avgPercentage > 0 && (
+            {Number.isFinite(avgPercentage) && avgPercentage > 0 && (
               <span className="text-muted-foreground text-[10px]">
                 {t('settings.providerGroupings.avgLabel')}
               </span>