Database code

[RohnanK]

Hello team,

I've made some changes to the database models by adding classes to the models file for various tables that we require. These changes are essential for storing User data, post data and study group data.

Changes Made:

• Added database models for Users, Posts, Study groups.
• The primary key is the student number which is a foreign key for the other tables.

Please review the changes and provide any feedback or suggestions. Let me know if there are any further modifications needed or if you have any questions.

Thank you!

[IsoVictor]

Looks good merge when ready!!!