enhance(frontend): 季節に応じた画面の演出を南半球に対応させる (#12838)

* (enhance) 季節に応じた画面の演出を南半球に対応させる

* Update Changelog

* (add) 半球の簡易自動判定

---------

Co-authored-by: syuilo <Syuilotan@yahoo.co.jp>

packages/frontend/src/scripts/intl-const.ts

@@ -33,6 +33,10 @@ try {
 }
 export const dateTimeFormat = _dateTimeFormat;
 
+export const timeZone = dateTimeFormat.resolvedOptions().timeZone;
+
+export const hemisphere = /^(australia|pacific|antarctica|indian)\//i.test(timeZone) ? 'S' : 'N';
+
 let _numberFormat: Intl.NumberFormat;
 try {
 	_numberFormat = new Intl.NumberFormat(versatileLang);