feat(locale): add English (United Kingdom) language

[hywax]

🔗 Linked issue

Resolves #5552 (comment)

❓ 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.

[benjamincanac]

@hywax Following up on #5552 (comment) here. I meant the translations are exactly the same as the en file. Did you check my solution with extendLocale? I'm not entirely against adding a British locale file but then we need to add hundreds of duplicates for each:

[pkg-pr-new]

npm i https://pkg.pr.new/@nuxt/ui@5561

commit: 09a750c

[hywax]

Well, actually, there will be some differences in each locale.

For example, we can take:

• https://github.com/nuxt/ui/blob/v4/src/runtime/locale/pt.ts
• https://github.com/nuxt/ui/blob/v4/src/runtime/locale/pt_br.ts

there aren't that many differences

If you are confused by the 98% of literals in the copy, you can do the following. But I repeat, the words are insignificant, they may differ.

import type { Messages } from '../types'
import { defineLocale } from '../composables/defineLocale'
import en from './en'

export default defineLocale<Messages>({
  name: 'English (British)',
  code: 'en-GB',
  messages: en.messages
})

[benjamincanac]

I think we should keep Nuxt UI's built-in locales at the language level only (en, fr, de, etc.) and avoid adding region variants when the translation content is identical. Otherwise, we'll end up maintaining a long list of duplicated locale files (en-US, en-CA, en-AU, etc.).

Although I'd recommend using extendLocale in most cases: const enGB = extendLocale(en, { code: 'en-GB' }), since en-GB is a particularly common locale and has been requested quite often, I think we can make an exception!