feat(25-02): add attribution display on catalog detail page

- GlobalItem interface extended with sourceUrl, imageCredit, imageSourceUrl fields
- Attribution block below image: Photo credit and source link when present
- Product page link (sourceUrl) at bottom of detail page
- Image div mb-6 moved to attribution paragraph for consistent spacing

src/client/hooks/useGlobalItems.ts

@@ -10,6 +10,9 @@ interface GlobalItem {
 	priceCents: number | null;
 	imageUrl: string | null;
 	description: string | null;
+	sourceUrl: string | null;
+	imageCredit: string | null;
+	imageSourceUrl: string | null;
 	createdAt: string;
 }