Bookmarks Cards Layout Style

### Description

I'd like to add card-based layout style for the bookmarks widget to provide a more visual and modern way to display bookmarks.
- Add a new style: cards option to the bookmarks widget
- Display bookmarks as a responsive grid of cards

Start by locating the bookmarks widget implementation and its existing style options. Trace how bookmarks are rendered, then add the cards option as a responsive grid while preserving the current styles. Done means the new layout is selectable and displays bookmarks as responsive cards.

Written by the indexing model from the issue text.