feat(lang): load from config

Author: hywax

Diff for: app.vue

@@ -7,8 +7,10 @@
 <script setup lang="ts">
 const siteConfig = useSiteConfig()
 const colorMode = useColorMode()
+const { locale } = useI18n()
 
 colorMode.preference = siteConfig.theme || 'system'
+locale.value = siteConfig.lang
 
 useHead({
   title: siteConfig.title,