Add sliver functionality with dynamic `AppBar`

[elibon99]

This PR implements enhancements to the scrolling behavior and AppBar interaction within the application.

Key changes:

• Enhanced Scrolling: The scrolling behavior has been refined to offer a smoother experience.
• Sliver functionality The main title remains pinned until a headerSliver (optional) is scrolled under it. This mainly concerns the OATH view in which the search field is first scrolled under the main title. Subesquently, when the main title is scrolled under the AppBar, the title is rendered there instead.