Implementing Persistent Redirection for Signed-In Users

[mlajkim]

At present, if you're already signed in and attempt to access http://localhost:3000/welcome directly, the system will redirect you to the main app page at http://localhost:3000.

We would like to implement the same mechanism for http://localhost:3000/signin. This way, even if a user signs in, is redirected to the main app page, and then clicks the back button, they will be forcibly redirected to the main app page again.