- Replace getRandomFallbackImage() with getFallbackImage(index) for deterministic fallback images
- Reduce advertisement count from 3 to 2 in News section
- Reduce sidebar advertisements from 5 to 3 in ArticleDetailPage
- Add image validation and optimization for SEO metadata
- Implement toOptimizedSeoImageUrl() to serve optimized images via Next.js image optimizer
- Add isRemoteImageValid() to verify remote image