Update warning text and fix missing price in cart

- Change warning to say 'approximate placement' instead of just 'placement'
- Add missing cartItemId, name, mockup, unitPrice, and preview URLs when adding design to cart
- Fixes NaN price display for designs added from approval page

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

src/app/cart/page.tsx

@@ -166,7 +166,7 @@ export default function CartPage() {
           <p className="font-medium text-ink">Please check your design before checking out</p>
           <p className="mt-1 text-muted">
             We print exactly what&apos;s shown in your preview above — spelling, wording, and
-            placement included. Once your order&apos;s placed, that design goes straight to print,
+            approximate placement included. Once your order&apos;s placed, that design goes straight to print,
             so take a moment to make sure everything looks right.
           </p>
         </div>

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

@@ -50,11 +50,22 @@ export default function DesignReviewPage({ params }: { params: { id: string } })
 
         // Add to cart
         addItem({
+          cartItemId: crypto.randomUUID?.() || Math.random().toString(36).substr(2, 9),
           productId: design.productId,
+          slug: design.product.id, // Using product ID as slug for now
+          name: design.product.name,
+          mockup: design.product.id,
           color: design.color,
           size: design.size,
-          designJson: design.designJson,
           quantity: 1,
+          unitPrice: design.product.effectivePrice,
+          designJson: design.designJson,
+          designPreviewUrl: design.designPreviewUrl,
+          designPreviewUrlBack: design.designPreviewUrlBack,
+          placementPreviewUrl: design.placementPreviewUrl,
+          placementPreviewUrlBack: design.placementPreviewUrlBack,
+          designWidthCm: null,
+          designHeightCm: null,
         });
 
         alert('Design approved! Added to your bag.');