Add focus-visible style for marketplace grid item selection

[Chucks1093]

Summary
Marketplace grid items lack a distinct focus-visible style, making keyboard navigation through the grid invisible. A focused grid item should show a clear indicator consistent with the rest of the UI focus ring system.

Scope

• locate the marketplace grid item component
• apply a focus-visible style using the project focus ring token or convention
• verify the style appears only on keyboard focus and not on mouse click

Acceptance Criteria

• keyboard focus on a grid item shows a visible focus ring
• mouse click on a grid item does not show the focus ring
• the style is consistent with focus rings used elsewhere in the UI

Contributor coordination: if you pick this up, reach out in Telegram for updates or clarification: https://t.me/accesslayerorg