refactor(shadow): introduce shadow-card utility and extend tailwind-merge

app/(order)/dispute/[id]/page.tsx

@@ -159,7 +159,7 @@ export default function DisputePage({ params }: { params: Promise<{ id: string }
           返回订单
         </Link>
 
-        <Card className="hover:shadow-[var(--shadow-card)]">
+        <Card className="hover:shadow-card-hover">
           <CardHeader>
             <div className="flex items-center justify-between">
               <CardTitle>争议详情</CardTitle>
@@ -393,7 +393,7 @@ export default function DisputePage({ params }: { params: Promise<{ id: string }
         返回订单
       </Link>
 
-      <Card className="hover:shadow-[var(--shadow-card)]">
+      <Card className="hover:shadow-card-hover">
         <CardHeader>
           <CardTitle className="flex items-center gap-2">
             <AlertTriangle className="h-5 w-5 text-yellow-500" />