revert: remove i18n lazy loading and highlight.js selective import (#736)

Revert the dynamic import() for i18n locales and highlight.js core+
registration from #696. Dynamic imports create separate chunk files
that cause 404 errors for users after updating when the browser still
references old chunk hashes.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

packages/client/src/main.ts

@@ -1,7 +1,7 @@
 import { createApp } from 'vue'
 import { createPinia } from 'pinia'
 import router from './router'
-import { i18n, setupI18n } from './i18n'
+import { i18n } from './i18n'
 import App from './App.vue'
 import './styles/global.scss'
 
@@ -36,6 +36,4 @@ const app = createApp(App)
 app.use(createPinia())
 app.use(i18n)
 app.use(router)
-setupI18n().then(() => {
-  app.mount('#app')
-})
+app.mount('#app')