fix(vue): make theme reactive

[HugoRCD]

🔗 Linked issue

resolve #3952

❓ 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)
• [ ] ✨ 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

📝 Checklist

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

[pkg-pr-new[bot]]

npm i https://pkg.pr.new/@nuxt/ui@3971

commit: 266e870

[nuxthub-admin[bot]]

✅ Deployed ui3

Deployed ui3 266e870e6793b9349af2c463aabdbf04154b0f63 to preview

🔗	fix-3952.ui-6q2.pages.dev
📌	0f63fc8f.ui-6q2.pages.dev
📱	View QR Code

📋 View deployment logs

[HugoRCD]

@HugoRCD Does this work with the useAppConfig composable imported from #imports defined in stubs.ts?

This doesn't work 😬

[benjamincanac]

Closing in favor of https://github.com/nuxt/ui/commit/869c0708bd351c7be44e5e430c348b19dd316db9.