datetime: user browser lang for date formatting

src/utils/time.ts

@@ -31,7 +31,7 @@ export const bounce = (
  *
  *   console.log(dateTime.format(new Date()));
  */
-export const dateTime = new Intl.DateTimeFormat('de-ch' /* navigator.language */, {
+export const dateTime = new Intl.DateTimeFormat(navigator.language /* navigator.language */, {
   dateStyle: 'medium',
   timeStyle: 'short',
 });