fix: Add OG image for /books page

[bobbyonmagic]

Problem

The books page at https://devops-daily.com/books is missing an Open Graph image.

When shared on social media (Twitter, LinkedIn, Slack, etc.), the page displays without a preview image, reducing engagement and click-through rates.

Expected

All public pages should have OG images for proper social media previews.

Fix Required

1. Create public/images/pages/books-og.svg (source)
2. Generate public/images/pages/books-og.png (1200x630)
3. Add metadata to app/books/page.tsx:

export const metadata: Metadata = {
  title: 'DevOps Books',
  description: 'Curated list of essential DevOps books...',
  openGraph: {
    title: 'DevOps Books',
    description: 'Curated list of essential DevOps books...',
    images: ['/images/pages/books-og.png'],
  },
  twitter: {
    card: 'summary_large_image',
    images: ['/images/pages/books-og.png'],
  },
}

Acceptance Criteria

• OG image created (1200x630px)
• Image displays correctly when sharing URL on Twitter/LinkedIn
• Can verify with https://www.opengraph.xyz/url/https%3A%2F%2Fdevops-daily.com%2Fbooks