Commit design approval workflow and related features

- Add design approval workflow components and API routes
- Update checkout process for design approval integration
- Add admin navigation for design management
- Update mail utilities for design notifications
- Update types for design approval system
- Update Prisma schema for design approval database

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

src/app/api/orders/[id]/design-spec/route.ts

@@ -249,6 +249,15 @@ export async function GET(req: Request, { params }: { params: { id: string } })
     <p><strong>Order ID:</strong> ${order.id}</p>
     <p><strong>Product:</strong> ${item.productName}</p>
     <p><strong>Color:</strong> ${item.color} ${item.size ? `| Size: ${item.size}` : ''}</p>
+    ${item.designWidthCm && item.designHeightCm ? `<p><strong>Design Dimensions (Overall):</strong> ${item.designWidthCm} cm × ${item.designHeightCm} cm</p>` : ''}
+    ${item.designImageDimensions ? (() => {
+      try {
+        const imageDims = JSON.parse(item.designImageDimensions);
+        return imageDims && imageDims.length > 0 ? `<p><strong>Image Dimensions:</strong><ul style="margin: 5px 0 0 20px;">${imageDims.map((img, idx) => `<li>Image ${idx + 1}: ${img.widthCm} cm × ${img.heightCm} cm</li>`).join('')}</ul></p>` : '';
+      } catch (e) {
+        return '';
+      }
+    })() : ''}
     <p><strong>Order Date:</strong> ${new Date(order.createdAt).toLocaleDateString()}</p>
   </div>