RFC: Login Frontend

[MinhxNguyen7]

Description

• Implement frontend changes for login system.
• Branch off of auth-backend.

Design

TO BE ELABORATED if Brian doesn't get this done soon and we delegate it.

Issues

• Related to #890

[ap0nia]

Steps left

• [ ] Properly set and read auth cookie.
• [ ] When user loads schedule, check visibility and allow certain permissions.
• [ ] Add ability to update username.
• [ ] Use electrodb.