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

app/(order)/orders/page.tsx

@@ -126,14 +126,14 @@ function OrderListContent({
 
         <TabsContent value={tab} className="mt-4 space-y-4">
           {filtered.length === 0 ? (
-            <Card className="hover:shadow-[var(--shadow-card)]">
+            <Card className="hover:shadow-card-hover">
               <CardContent className="py-8 text-center text-sm text-muted-foreground">
                 暂无订单
               </CardContent>
             </Card>
           ) : (
             filtered.map((order) => (
-              <Card key={order.id} className="hover:shadow-[var(--shadow-card)]">
+              <Card key={order.id} className="hover:shadow-card-hover">
                 <CardHeader className="pb-3">
                   <div className="flex items-center justify-between">
                     <CardTitle className="text-base">{order.service.title}</CardTitle>