Mobile Cart Empty

User story

As a mobile user, I want to see a clear empty state for the shopping cart, so I understand when no items have been added to my cart.

Acceptance criteria

• Clicking the cart icon with 0 items shows an empty cart state.
• The view includes a back arrow and "Shopping Cart" label, similar to the desktop layout.
• A message is displayed indicating that the cart is empty, encouraging users to add items.