feat: add basic admin dashboard

inertia/components/lang_selector.tsx

@@ -1,3 +1,4 @@
+import dayjs from 'dayjs';
 import { ChangeEvent } from 'react';
 import { useTranslation } from 'react-i18next';
 import { LS_LANG_KEY } from '~/constants';
@@ -9,6 +10,7 @@ export default function LangSelector() {
   const onToggleLanguageClick = ({
     target,
   }: ChangeEvent<HTMLSelectElement>) => {
+    dayjs.locale(target.value);
     i18n.changeLanguage(target.value);
     localStorage.setItem(LS_LANG_KEY, target.value);
   };