chore: use eslint flat config and add oxlint

[zoey-kaiser]

🔗 Linked issue

closes N/A

❓ 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

Updates our pretty outdated linting setup to make it more modern:

• Switch to Eslint flat config and use @antfu/eslint-config as a base
• Add OxLint to catch additional errors

📝 Checklist

• I have linked an issue or discussion.
• I have added tests (if possible).
• I have updated the documentation accordingly.

[zoey-kaiser]

@phoenix-ru I have noticed that the playground tests fail pretty quickly when updating the dependencies of the root package.json. This was also one of the reasons why I installed vitepress inside another package.json inside the /docs directory.

In this PR I wanted to update our linter and installing oxlint already broke the tests. The error messages thrown by the tests are pretty crypic to me. Do you have any ideas on how we can make the tests rely less on the root package.json and be isolated to their own workspaces? I assume the issue comes from new dependency linkages that may use other versions of sub-dependencies then they do. However, as you are the experts on the tests, I wanted to pass this onto you, in case you has specific limitation / concerns about this 🤗

[zoey-kaiser]

Waiting on #818