Update Dashboard Coupons Card

[atorresveiga]

For the background project update we need to:

- [ ] Show cached content
- [ ] Save and display last sync timestamp
- [ ] Add loading indicator when the content is being loaded
- [ ] Refresh data in a background task 
- [ ] Make sure stale data is refreshed when the view appears

[dangermattic]

🚫 Please add a type label (e.g. type: enhancement) and a feature label (e.g. feature: stats) to this issue.