Improve the UI for Pretty JSON

[mmabrouk]

Pretty JSON needs UI improvements. Reported issues include low contrast and spacing, no clear distinction between keys and values, and a hard-to-discover copy action. The current hover behavior for copy is fine, but the UI itself needs improvement.

[linear-code]

AGE-3784

[mohammadhouda]

hey @mmabrouk , i would like to work on this one.