✨ feat(dashboard): update key metrics display

- change metric from "储备仓容" to "辐射带动面积"
- update value from "?000" to "20" with unit changed from "万吨" to "万亩"
- adjust digits display to ['>', '2', '0']

src/client/home/pages/SupplyChainDashboards/components/KeyMetrics.tsx

@@ -69,10 +69,10 @@ const KeyMetrics: React.FC<KeyMetricsProps> = ({
       digits: ['1', '5']
     },
     {
-      title: "储备仓容",
-      value: "?000",
-      unit: "万吨",
-      digits: ['?', '0', '0', '0']
+      title: "辐射带动面积",
+      value: "20",
+      unit: "万亩",
+      digits: ['>', '2', '0']
     }
   ];