Fix: Minor UI fixes for notifications tab

[davecreaser]

Description

• Fix some minor UI issues with the notifications tab
  • Add a border bottom to each notification (matching the transactions tab)
  • Add a hover state to the 'Mark all as read' button (gray-900)
  • Align the padding top and bottom of the notifications items with the design (14px or 0.875rem - also matching the transactions tab)

Testing

• Make a couple of simple payments or mint tokens actions or something simple, so that you have a few notifications.

• Check that there is a border bottom on each item, which matches the border bottom of the transactions in the transactions tab.

• Check that when you hover over 'Mark all as read' it turns gray-900

• Check that the padding top and bottom of each item is correct

Figma:

Localhost:

Diffs

Changes 🏗

• Classname tweaks to userhub / notifications components

Resolves #3667

[bassgeta]

Looking good 👌


Can't see the cursor here, but I have hovered over Mark all as read

Shall we add the notification.id to the useMemo deps so we don't get orange triangle warnings in Github 👀 ?