fix: #3227 show traffic chart only when data is available

src/components/home/enhanced-traffic-stats.tsx

@@ -401,10 +401,12 @@ export const EnhancedTrafficStats = () => {
 
   return (
     <Grid container spacing={1} columns={{ xs: 8, sm: 8, md: 12 }}>
-      <Grid size={12}>
-        {/* 流量图表区域 */}
-        {trafficGraphComponent}
-      </Grid>
+      {trafficGraph && (
+        <Grid size={12}>
+          {/* 流量图表区域 */}
+          {trafficGraphComponent}
+        </Grid>
+      )}
       {/* 统计卡片区域 */}
       {statCards.map((card, index) => (
         <Grid key={index} size={4}>

src/pages/home.tsx

@@ -322,7 +322,6 @@ export const HomePage = () => {
               title={t("Traffic Stats")}
               icon={<SpeedOutlined />}
               iconColor="secondary"
-              minHeight={280}
             >
               <EnhancedTrafficStats />
             </EnhancedCard>