Interface CartItem

interface CartItem {
    id: number;
    product: Product;
    variant: ProductVariant;
    design: null | CustomDesign;
    quantity: number;
    custom_text: string;
    custom_number: string;
    line_total: string;
    design_cost_breakdown?: null | DesignCostBreakdown;
    added_at?: string;
    updated_at?: string;
}