Include toggle option on cards so that they can be 'selected/unselected/

## Summary
Cards currently allow this using a checkbox on the card, whereas the user expectation is that the whole card should be clickable and then selected.

## 💬 Description
Need a selection state on cards that doesn't rely solely on colour. The introduction of a 'selection bar' similar to tabs, side nav and other selectable components could be a good solution to try.

## 💰 Use value
Provides greater functional flexibility on cards so that they can be used for wider array of situations.

## Additional info
Tell us anything else useful to help us understand your suggestion.

Start by reviewing the existing card component and the selection patterns used by tabs and side navigation. Determine how whole-card selection should expose selected and unselected states without relying only on colour, then confirm the interaction and visual behavior for the proposed selection bar before implementation.

Written by the indexing model from the issue text.