Resolve assigning administrators to school

[AmonDeShir]

Currently, every user, including administrators, is assigned a school. This creates a problem because the school with ID 1, created by the seeder for the super admin, appears as an option during user registration. This results in a misleading choice for users, as they may select a school that doesn’t actually exist. Additionally, this school may show up in rankings and in the school CRUD page, where administrators could accidentally delete it, potentially removing all assigned administrators.

To resolve this, we need to either restructure the user system by separating students and administrators into different models, or reserve school with ID 1 (created by the seeder) only for administrators. This school could be marked as "disabled" and automatically assigned when creating new administrator accounts.