feat: add homepage and contacts(to-do)

components/footer.tsx

@@ -0,0 +1,7 @@
+export default function Footer() {
+  return (
+    <footer className="w-full bg-white shadow p-4 text-left text-gray-500">
+      <p>© {new Date().getFullYear()} 智能计算实验室</p>
+    </footer>
+  );
+}

components/header.tsx

@@ -0,0 +1,12 @@
+import Link from "next/link";
+
+export default function Header() {
+  return (
+    <header className="w-full bg-white shadow p-4 flex justify-between items-center">
+      <h1 className="text-2xl font-bold text-gray-900">智能计算实验室</h1>
+      <nav>
+        <Link href="/contacts" className="text-blue-600 hover:underline">联系人</Link>
+      </nav>
+    </header>
+  );
+}