Fix: Pass photo request ID instead of data URL

Changed approach to pass customRequestId query parameter instead of
the full data URL. The design canvas page now fetches the photo from
the database using the request ID, avoiding URL length issues and
making the URL cleaner.

src/app/admin/custom-requests/[id]/page.tsx

@@ -19,7 +19,7 @@ export default async function CustomRequestDetailPage({ params }: { params: { id
   const whatsappMessage = `Hi ${request.customerName}, thanks for sending over your photo for a ${request.product.name} — we're working on it!`;
 
   const designParams = new URLSearchParams({
-    customPhoto: request.imageDataUrl,
+    customRequestId: request.id,
   });
 
   return (