feat: add initial frontend setup with styles, types, and testing framework

- Created a global CSS file for styling the frontend with responsive design.
- Introduced TypeScript types for various entities including Research, Alpha, and Account.
- Implemented Playwright tests for account management and data synchronization workflows.
- Configured TypeScript with strict settings and included necessary libraries.
- Set up Vite as the build tool with React plugin and API proxy configuration.
- Added a Python script to initialize environment variables securely.

frontend/src/main.tsx

@@ -0,0 +1,11 @@
+import "@douyinfe/semi-ui-19/react19-adapter";
+import React from "react";
+import ReactDOM from "react-dom/client";
+import App from "./App";
+import "./style.css";
+
+ReactDOM.createRoot(document.getElementById("root")!).render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>,
+);