feat: enhance SEO and social media metadata

[Waynemandem]

📋 Changes Made

This PR improves the SEO and social media sharing capabilities of the web app by enhancing the metadata in index.html.

✨ Improvements:

• ✅ Updated meta description for better search engine visibility
• ✅ Added Open Graph tags for rich social media previews (Facebook, LinkedIn)
• ✅ Added Twitter Card metadata for better Twitter sharing
• ✅ Added keywords meta tag for SEO
• ✅ Added author information
• ✅ Improved page title for clarity and SEO
• ✅ Added performance optimization with preconnect to GitHub API
• ✅ Added accessibility meta tag for color scheme preference

🎯 Benefits:

• Better discoverability on search engines
• Improved sharing experience on social media platforms
• Faster API calls through DNS preconnect
• Better accessibility support

📸 Testing:

• ✅ Tested locally with npm start
• ✅ No console errors
• ✅ All meta tags render correctly in browser DevTools

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This is my first contribution to open source! 🎉