add main menu to ui
validate and puts error messages for too short/long passwords, add create new clerk method
add login_menu method
fix login method to cycle through all names instead of exiting after first
add add_inventory and update_item methods
add transaction menu and add_to_cart method
add view_cart and remove_from_cart method; add new migration for purchases table (adds 'total' column)
add cancel_transaction method and fixes prices/total to puts in float format
divides ui methods into seperate files; add current user display
add validations and validation specs for all classes; add error checks in ui
complete readme.md