fix(prerender): extract links from explicit html routes

[danielroe]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 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

Discovered while triaging nuxt/nuxt#27490 (which is a bug in Nuxt). We are not crawling paths that are prerendered with an explicit .html suffix.

It feels like this might be an oversight, and we could benefit from this in Nuxt (adding prerender headers when rendering 200.html) but if you think it might pose any issues, feel free to close.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[pi0]

Quick look seems good. It would be nice if you can add it to the tests mainly because i am planning to have some major refactors on prerenderer and don't want it to cause a regression with fix of this PR