waltpianist97/teamUp-app ? reverse-engineered prompt

Build me a simple Flask web app for user sign up and log in.

I want a clean site where people can create an account, sign in, and log out, with basic form checks so empty or bad entries are handled nicely. After login, show a simple welcome page or dashboard, and if someone is not logged in, send them back to the login page. Please make the pages look tidy and easy to use, with a clear navigation flow between register, login, and logout.

Use the existing project structure, templates, static files, forms, routes, and models as needed, and keep the app easy to run locally. If anything in the Flask setup needs current best practices or docs, look them up online if needed. Also add a little sample data or whatever is needed so I can test the full flow quickly.