fix(nuxi): add back default baseUrl in tsconfig.json

[danielroe]

🔗 Linked issue

follow up on #21070, #21081

❓ 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)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This PR partially reverts the change in #21081, defering the change to typescript.compilerOptions.baseUrl until Nuxt 3.7, as we have tooling (notably our internal eslint-config) that currently relies on baseUrl being set.

It does aim to be compatible with removing baseUrl, for users who want to opt in early, by using absolute paths for aliases.

It should also give us longer to confirm that the normalisation changes (converting inferred relative paths to explicit ones) continue to work for a non-breaking upgrade path.

📝 Checklist

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