async function updateDashboard() {
    try {
        const res = await fetch('/api/stats');
        const data = await res.json();
        
        if (data && data.length > 0) {
            // 비트코인 표시
            const btc = data.find(item => item.symbol === 'BTC');
            if (btc && btc.current_price > 0) {
                document.getElementById('btc-price').innerText = `${Math.floor(btc.current_price).toLocaleString()} 원`;
                const change = (btc.change_rate * 100).toFixed(2);
                const changeEl = document.getElementById('btc-change');
                changeEl.innerText = `${change > 0 ? '▲' : '▼'} ${Math.abs(change)}%`;
                changeEl.className = `text-sm font-bold ${change > 0 ? 'text-rose-500' : 'text-blue-500'}`;
            }

            // 환율 표시
            const usd = data.find(item => item.symbol === 'USD/KRW');
            if (usd && usd.current_price > 0) {
                document.getElementById('usd-price').innerText = `${parseFloat(usd.current_price).toFixed(2)} 원`;
                document.getElementById('usd-time').innerText = `Last Update: ${new Date(usd.updated_at).toLocaleTimeString()}`;
            }
        }
    } catch (e) { console.error('조회 실패:', e); }
}