fix(usage): make model stats card scrollable

src/components/usage/ModelStatsCard.tsx

@@ -59,10 +59,11 @@ export function ModelStatsCard({ modelStats, loading, hasPrices }: ModelStatsCar
     sortKey === key ? (sortDir === 'asc' ? 'ascending' : 'descending') : 'none';
 
   return (
-    <Card title={t('usage_stats.models')}>
+    <Card title={t('usage_stats.models')} className={styles.detailsFixedCard}>
       {loading ? (
         <div className={styles.hint}>{t('common.loading')}</div>
       ) : sorted.length > 0 ? (
+        <div className={styles.detailsScroll}>
           <div className={styles.tableWrapper}>
             <table className={styles.table}>
               <thead>
@@ -149,6 +150,7 @@ export function ModelStatsCard({ modelStats, loading, hasPrices }: ModelStatsCar
               </tbody>
             </table>
           </div>
+        </div>
       ) : (
         <div className={styles.hint}>{t('usage_stats.no_data')}</div>
       )}

src/pages/UsagePage.module.scss

@@ -580,6 +580,26 @@
   }
 }
 
+// Fixed-height cards with internal scrolling (API details / model stats)
+.detailsFixedCard {
+  display: flex;
+  flex-direction: column;
+  height: 520px;
+  overflow: hidden;
+
+  @include mobile {
+    height: 420px;
+  }
+}
+
+.detailsScroll {
+  flex: 1 1 auto;
+  min-height: 0;
+  overflow: auto;
+  -webkit-overflow-scrolling: touch;
+  overscroll-behavior: contain;
+}
+
 // Table (80%比例)
 .tableWrapper {
   overflow-x: auto;