Carol-here/SecureBlackboard ? reverse-engineered prompt

Build me a secure blackboard app where people can sign in, post notes or announcements, and view everything in a simple clean web app.

I want a working full stack project with a frontend, a backend, and an easy local setup so I can run it with Docker. It should feel like a private shared board, so include basic authentication, protected access, and a straightforward way to add, edit, and delete posts. Make the interface simple and easy to use, with a nice board style layout and clear navigation.

Please set up the project so it is organized, easy to run locally, and ready for future features. If you need current best practices or library details, look up the latest docs online. Also add a short README that explains how to start it and what it does.