feat: setup next.js project

frontend/src/App.tsx

@@ -1,14 +0,0 @@
-import React from "react";
-import FeedList from "./components/FeedList";
-import EpisodeList from "./components/EpisodeList";
-
-export default function App() {
-  return (
-    <div style={{ padding: "20px", fontFamily: "sans-serif" }}>
-      <h1>ポッドキャスト自動生成サービス 管理画面</h1>
-      <FeedList />
-      <hr style={{ margin: "20px 0" }} />
-      <EpisodeList />
-    </div>
-  );
-}

frontend/src/index.tsx

@@ -1,6 +0,0 @@
-import React from "react";
-import ReactDOM from "react-dom/client";
-import App from "./App";
-
-const root = ReactDOM.createRoot(document.getElementById("root")!);
-root.render(<App />);