fix: format date according to DEFAULT_LOCALE in chat search (#19305)

* fix: localized format

* load default_locale from backend

src/routes/+layout.svelte

@@ -54,6 +54,7 @@
 	import AppSidebar from '$lib/components/app/AppSidebar.svelte';
 	import Spinner from '$lib/components/common/Spinner.svelte';
 	import { getUserSettings } from '$lib/apis/users';
+	import dayjs from 'dayjs';
 
 	const unregisterServiceWorkers = async () => {
 		if ('serviceWorker' in navigator) {
@@ -666,6 +667,7 @@
 				? backendConfig.default_locale
 				: bestMatchingLanguage(languages, browserLanguages, 'en-US');
 			changeLanguage(lang);
+			dayjs.locale(lang);
 		}
 
 		if (backendConfig) {