Google登入功能開發

1. Get a Google Client ID

- Go to https://console.cloud.google.com/

- Create a project (or use existing)

- Go to APIs & Services → Credentials

- Click Create Credentials → OAuth 2.0 Client ID

- Set application type to Web application

- Add your frontend's origin to Authorized JavaScript origins (e.g. http://localhost:5173)

- Copy the Client ID

2. Set the environment variable

GOOGLE_CLIENT_ID=your-client-id-here.apps.googleusercontent.com