Get basket information

This is the "full pricing breakdown" endpoint.

Call this right before checkout (or on a checkout review screen) when you need:

• basket summary totals
• platform/service fee
• delivery costs calculated per seller

What makes it useful:

• Delivery is computed from each seller's delivery configuration.
• You get one payload with the financial details needed to render final pricing.

Heads up:

• This endpoint requires an authenticated user.