perf(nuxt): import defineNuxtConfig from nuxt/config

[pi0]

🔗 Linked issue

resolvesnuxt/nuxt#14821

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 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)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This PR introduces new nuxt/config subpath export with CJS+MJS build to avoid jiti extra transformations.

Also using jiti aliases, nuxt is aliases to nuxt/config within nuxt.config file. This way we transparently introduce this enhancement to all nuxt 3 users.defineNuxtConfig from nuxt is deprecated. Pending docs/examples update to after release and try. Alias seemed little bit hacky to do and causing potential breaking changes.

📝 Checklist

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

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[atinux]

Shall we open an issue to keep track of updating it for documentation?