refactor out `/deck/:deck_id/card/:card_id`

[x] complete
rationale: not clear on which deck card actually belongs to, and thus is very confusing
refactor plan
[x] replace with /card/:card_id route
[x] breadcrumb should point to card's actual/real deck path
refactor context aware breadcrumb
[x] complete
refactor plan
[x] when viewing a card or list of cards, go to list of cards of "next deck id"
[x] when viewing deck route, go to same deck route of "next deck id"
better card list item UI component
[ ] complete
refactor plan
[ ] show/hide extra details
[ ] display card's deck path

dashed / grokdb2