Fix scrolling behavior on Applications listing page

### Description

On the Applications listing page, the search bar currently scrolls together with the applications list. Update the layout so that:

- The search bar is sticky at the top
- Only the applications list below it scrolls
- Add a
(or equivalent spacing) between the search bar and the applications list to visually separate the sticky header from the scrollable content

### Epic/Story

_No response_

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate