Make user-page (with all permanently set settings, to give an overview!)

[hmpf]

The Argus HTMX front-end currently only features a few user settings in the top-right dropdown menu:

More user settings will be added in the future. Having all of them in the dropdown menu is a no-go. We should build a user settings page that enables users to have a main page for all their Argus settings, not just "quick-settings".

Initially, this page may only include the same settings items as the dropdown menu, but it should be easily expandable later.