Add dynamic OG image generation for social media sharing

## Features
- Create /api/og route for dynamic Open Graph image generation
- Beautiful gradient design with site branding
- Display post title, description, and tags
- Support for both light and dark themes
- Proper sizing for social media (1200x630)

## Implementation
- Use @vercel/og package for image generation
- Add OpenGraph and Twitter Card metadata to blog posts
- Fallback to localhost for development
- Uses NEXT_PUBLIC_SITE_URL environment variable for production

## Social Media Support
- OpenGraph (Facebook, LinkedIn, etc.)
- Twitter Cards with large image preview
- Article metadata including publish time and tags

Example usage:
/api/og?title=Post+Title&description=Post+Desc&tags=tag1,tag2,tag3

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

package.json

@@ -21,6 +21,7 @@
     "@fortawesome/free-brands-svg-icons": "^7.1.0",
     "@fortawesome/free-solid-svg-icons": "^7.1.0",
     "@fortawesome/react-fontawesome": "^3.1.0",
+    "@vercel/og": "^0.8.5",
     "clsx": "^2.1.1",
     "contentlayer2": "^0.5.8",
     "framer-motion": "^12.23.24",