Changes

tsk24: Implements User entity and story authorship
A new User entity has been introduced to represent application users, 
including properties for authentication and role management via a new 
UserType enum. The Story entity was updated to establish a mandatory 
Many-to-One relationship with the User, representing the author of the 
content. This change involved updating the database schema definitions 
to include the user table and foreign key constraints, as well as 
modifying the data insertion scripts. Additionally, unit tests for the 
new entity were created, and existing integration tests and datasets 
were adjusted to account for the required author association.