fix(storage): respect category hide_globally when marking all as read

The "Mark all as read" button on the Unread page calls
MarkGloballyVisibleFeedsAsRead, which only filtered on feeds.hide_globally
and ignored the feed's category. Entries belonging to a category marked as
hidden from the global unread list were therefore marked as read even though
they are not shown on that page.

Join the categories table and exclude both feeds and categories that are
hidden globally, matching the visibility rules already used by the unread
query builder, the pagination builder and the navigation unread counter.

Fixes #4444