修复前端报错

frontend/src/pages/Dashboard.tsx

@@ -78,7 +78,7 @@ export function Dashboard() {
       {/* Stats */}
       <div style={{ display: 'grid', gridTemplateColumns: 'repeat(3, 1fr)', gap: 20 }}>
         {loading ? (
-          STAT_CARDS.map((c, i) => (
+          STAT_CARDS.map((_c, i) => (
             <div key={i} style={{
               background: '#fff', borderRadius: 12, padding: '20px 24px',
               boxShadow: '0 1px 3px rgba(0,0,0,0.06)', border: '1px solid rgba(0,0,0,0.04)',