perf(nuxt): prevent head dom from rendering twice

[harlan-zw]

🔗 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

With the move to immediately rendering the dom instead of debouncing it, we've introduced a regression in that the head will render to the DOM twice.

While the performance impact of this is reduced by quite a bit with Unhead 1.3, it's still not ideal and maybe adding ~5ms of extra load time.

The underlying issue is that we should wait for the suspense to resolve if we know the app is hydrating.

📝 Checklist

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

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