feat: add Bluesky account link on footer

[shuuji3]

🔗 Linked issue

resolve #345

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 📰 Content (a new article or a change in the content folder)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

As written in the original issue, not having a Bluesky link makes it a bit difficult for new users to find a Bluesky account.

This PR adds two changes:

• add Bluesky account icon link on the footer
• adjust LD+JSON for the website to include Bluesky account profile

This helps new users find an account in an open platform where anyone who has Internet access can see the latest posts, unlike the other closed social media.

(with new Bluesky link icon)

(when hovering the mouse cursor)

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.
  • N/A for docs

[shuuji3]

I kept the original links here. But if UnJS Twitter account will no longer be active, I can also remove this link from the website.

[shuuji3]

I also noticed there are other twitter links in Blog post etc. If you'd like to update those, I can help update them as well (by this PR or the other PR).

[shuuji3]

Aside from that, it'd be nice to add a Bluesky account link to unjs org profile too: https://github.com/unjs

[pi0]

Thanks for nice work and suggstion. I have updated org, this repository needs little bit maintenance first.

[shuuji3]

I made a separate PR to fix the lint errors on main branch: #347. This would solve the current CI failure. It needed only a few lines of change.