Feat: Show estimated delivery date on design review page

- Add expectedDeliveryDate to DesignApproval interface
- Display estimated delivery date in Order Summary section
- Shows the date set by admin when approving the design

Customers can now see when their design will be delivered
before adding it to their bag.

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

src/app/designs/[id]/review/page.tsx

@@ -22,6 +22,7 @@ interface DesignApproval {
   color: string;
   size: string | null;
   status: string;
+  expectedDeliveryDate: string | null;
 }
 
 export default function DesignReviewPage({ params }: { params: { id: string } }) {
@@ -167,6 +168,11 @@ export default function DesignReviewPage({ params }: { params: { id: string } })
               <p className="border-t border-line pt-3">
                 <strong>Price:</strong> £{((design.product.personalisedPrice ?? design.product.effectivePrice) / 100).toFixed(2)}
               </p>
+              {design.expectedDeliveryDate && (
+                <p className="text-xs text-muted pt-2">
+                  <strong>Est. delivery:</strong> {new Date(design.expectedDeliveryDate).toLocaleDateString(undefined, { dateStyle: 'medium' })}
+                </p>
+              )}
             </div>
 
             <button