Uniformize /search items

When searching for an item, books games and music already show an "Add" button but Videos dont: I have to uniformize that: a "+" button visible on hover on the items. Top right corner. Removing old "Add" button at the bottom of the cards.

Videos items have little transform on hover, other domains dont. I have to add the same style on cards of other domains.

I'd like also to add a little marker when an item is already in the user's library. So instead of showing "+" on hover, we show a checkmark (or something else, TBD) always (not only on hover) to inform the element is already followed.