feat(lang): add i18n feature

[kiaking]

• close Add I18N feature #359

Here we go. I've used Trans inspired by Laravel 👀 Now, we have everything in Sefirot, so I don't think we need to create Lang related things in App except for switching locale and stuff.

This PR only contains localization for required rule, but it shouldn't have breaking change, and localization support can be added incrementally.

// In App.vue
import { provideLang } from 'sefirot/composables/Lang'

const lang = getAppLang()

provideLang(lang)

// Validation rule definition.
import { createRule } from '../Rule'
import { required as baseRequired } from '../validators'

export const message = {
  en: 'The field is required.',
  ja: 'この項目は必須です。'
}

export function required(msg?: string) {
  return createRule({
    message: ({ lang }) => msg ?? message[lang],
    validation: (value) => baseRequired(value)
  })
}

[netlify]

✅ Deploy Preview for sefirot-story ready!

Name	Link
🔨 Latest commit	9930648
🔍 Latest deploy log	https://app.netlify.com/sites/sefirot-story/deploys/6582a3d861c2f400086e578b
😎 Deploy Preview	https://deploy-preview-421--sefirot-story.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[netlify]

✅ Deploy Preview for sefirot-docs ready!

Name	Link
🔨 Latest commit	9930648
🔍 Latest deploy log	https://app.netlify.com/sites/sefirot-docs/deploys/6582a3d88d624200087b8a10
😎 Deploy Preview	https://deploy-preview-421--sefirot-docs.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.