kr-aashay/Student_Mess_Bill_Calculation_System ? reverse-engineered prompt

Build me a simple student mess bill management app with a clean web interface and a Flask backend.

I want students to be able to register, log in with their student ID and phone number, and see their monthly bill history. I also want an admin login that can add monthly mess expenses, record how many days each student was present, and automatically calculate each student’s share based on attendance. Make sure the app saves everything in a database and uses secure login for both students and admins.

Please include basic pages for registration and login, and make the flow easy to use for someone who is not technical. If you need to check current Flask or JWT setup details, look them up online. Also, handle common errors nicely, like missing fields, wrong login details, or trying to enter the same month twice.