Explore other i18n solutions for `backend`s

Currently, we're using `petite-vue-i18n` for backend, this is great in case we want to reuse shared translations with Vue/Nuxt frontends, and/or using the same i18n syntax, but, `[petite-]vue-i18n` requires `vue` to be bundled to the runtime and can be troublesome in runtimes like Cloudflare Workers where we have limited code size restriction.