Add tooltip to GitHub links (repos & PRs)

[O2sa]

Repository and PR titles are clickable, but there is no visual hint that they open GitHub.

We want to improve UX by adding a tooltip when hovering over these links.

🎯 Expected Behavior

• When user hovers over a repo or PR title → show tooltip:
  "Open on GitHub"

✅ Tasks

• Add tooltip to all external GitHub links (repos & PRs)
• Ensure tooltip appears on hover
• Keep styling consistent

💡 Hints

• Use the title attribute for a simple solution:

<a href={url} title="Open on GitHub">
  {title}
</a>