fix: strict args

[Teages]

🔗 Linked issue

#148

❓ 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

Resolves #148

I noticed that citty didn't provide null-safety on context.args even strict is true, this will break some type checks. In this pr I make all args be nullable first, then make required and items with default values ​​non-nullable.

And ParsedArgs type has some errors when parsing enum, it just return the options array itself but the correct should be the type of items in the array. In this pr I just simplly fixed it, but the best fix should make the type more precise.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly. (N/A)

[Teages]

oops I just noticed #132, sorry to bother you :(