feat: add portfolio list page

frontend/src/app/portfolio/page.tsx

@@ -0,0 +1,126 @@
+'use client';
+
+import { useEffect, useState } from 'react';
+import { useRouter } from 'next/navigation';
+import Link from 'next/link';
+import Sidebar from '@/components/layout/Sidebar';
+import Header from '@/components/layout/Header';
+import { api } from '@/lib/api';
+
+interface Portfolio {
+  id: number;
+  name: string;
+  portfolio_type: string;
+  created_at: string;
+  updated_at: string;
+}
+
+interface User {
+  id: number;
+  username: string;
+  email: string;
+}
+
+export default function PortfolioListPage() {
+  const router = useRouter();
+  const [user, setUser] = useState<User | null>(null);
+  const [loading, setLoading] = useState(true);
+  const [portfolios, setPortfolios] = useState<Portfolio[]>([]);
+  const [error, setError] = useState<string | null>(null);
+
+  useEffect(() => {
+    const init = async () => {
+      try {
+        const userData = await api.getCurrentUser() as User;
+        setUser(userData);
+        await fetchPortfolios();
+      } catch {
+        router.push('/login');
+      } finally {
+        setLoading(false);
+      }
+    };
+    init();
+  }, [router]);
+
+  const fetchPortfolios = async () => {
+    try {
+      setError(null);
+      const data = await api.get<Portfolio[]>('/api/portfolios');
+      setPortfolios(data);
+    } catch (err) {
+      const message = err instanceof Error ? err.message : 'Failed to fetch portfolios';
+      setError(message);
+    }
+  };
+
+  const getTypeLabel = (type: string) => {
+    return type === 'pension' ? '퇴직연금' : '일반';
+  };
+
+  if (loading) {
+    return (
+      <div className="min-h-screen flex items-center justify-center">
+        <div className="text-gray-500">Loading...</div>
+      </div>
+    );
+  }
+
+  return (
+    <div className="flex min-h-screen">
+      <Sidebar />
+      <div className="flex-1">
+        <Header username={user?.username} />
+        <main className="p-6">
+          <div className="flex justify-between items-center mb-6">
+            <h1 className="text-2xl font-bold text-gray-800">포트폴리오</h1>
+            <Link
+              href="/portfolio/new"
+              className="px-4 py-2 bg-blue-600 text-white rounded hover:bg-blue-700 transition-colors"
+            >
+              새 포트폴리오
+            </Link>
+          </div>
+
+          {error && (
+            <div className="bg-red-100 border border-red-400 text-red-700 px-4 py-3 rounded mb-4">
+              {error}
+            </div>
+          )}
+
+          <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-4">
+            {portfolios.map((portfolio) => (
+              <Link
+                key={portfolio.id}
+                href={`/portfolio/${portfolio.id}`}
+                className="bg-white rounded-lg shadow p-6 hover:shadow-lg transition-shadow"
+              >
+                <div className="flex justify-between items-start mb-2">
+                  <h2 className="text-lg font-semibold text-gray-800">
+                    {portfolio.name}
+                  </h2>
+                  <span className={`text-xs px-2 py-1 rounded ${
+                    portfolio.portfolio_type === 'pension'
+                      ? 'bg-purple-100 text-purple-800'
+                      : 'bg-gray-100 text-gray-800'
+                  }`}>
+                    {getTypeLabel(portfolio.portfolio_type)}
+                  </span>
+                </div>
+                <p className="text-sm text-gray-500">
+                  생성일: {new Date(portfolio.created_at).toLocaleDateString('ko-KR')}
+                </p>
+              </Link>
+            ))}
+
+            {portfolios.length === 0 && !error && (
+              <div className="col-span-full text-center py-12 text-gray-500">
+                아직 포트폴리오가 없습니다. 새 포트폴리오를 생성해보세요.
+              </div>
+            )}
+          </div>
+        </main>
+      </div>
+    </div>
+  );
+}