As a logged-in customer, I want to be able to have a persistent cart so I can revisit and pick up where I left off

[Dee-bugg]

• Logged-in-user across multiple devices: I'm logged in on my mobile device and add some items to my cart. When I open the browser on my laptop and log in, I want to see those items in my cart.
• No one else should be able to edit my cart except me.