feat: add price, url, image, description, archived fields to Product struct

Extends the Product struct to include additional fields from the Snipcart
Products API response, enabling filtering of archived products and access
to product metadata like images and URLs.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

snipcart/snipcart.go

@@ -167,6 +167,11 @@ type Product struct {
 	Token          string               `json:"id"`
 	Id             string               `json:"userDefinedId"`
 	Name           string               `json:"name"`
+	Price          float64              `json:"price"`
+	Url            string               `json:"url"`
+	Image          string               `json:"image"`
+	Description    string               `json:"description"`
+	Archived       bool                 `json:"archived"`
 	Stock          int                  `json:"stock"`
 	TotalStock     int                  `json:"totalStock"`
 	AllowBackorder bool                 `json:"allowOutOfStockPurchases"`