Fix: Use personalised price in design approval cart add

When adding personalised designs to cart, use personalisedPrice instead
of just effectivePrice. This ensures the cart shows the correct price
for made-to-order items from the start, matching what Stripe calculates.

.claude/settings.local.json

@@ -65,7 +65,8 @@
       "Bash(git revert *)",
       "Bash(git commit -m 'Fix price display issues and layout in design review page *)",
       "Bash(git commit -m 'Fix: Calculate effectivePrice in design API endpoints *)",
-      "Bash(git commit -m 'Fix: Handle designJson as string in checkout API *)"
+      "Bash(git commit -m 'Fix: Handle designJson as string in checkout API *)",
+      "Bash(git commit -m 'Fix: Use personalised price in design approval cart add *)"
     ]
   }
 }

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

@@ -58,7 +58,7 @@ export default function DesignReviewPage({ params }: { params: { id: string } })
           color: design.color,
           size: design.size,
           quantity: 1,
-          unitPrice: design.product.effectivePrice,
+          unitPrice: design.product.personalisedPrice ?? design.product.effectivePrice,
           designJson: design.designJson,
           designPreviewUrl: design.designPreviewUrl,
           designPreviewUrlBack: design.designPreviewUrlBack,