chore: delete unused lang util function

Author: ryoppippi

2025/src/i18n/index.ts

@@ -2,14 +2,6 @@ export const LANGUAGES = ['ja', 'en'] as const;
 
 type Lang = typeof LANGUAGES[number];
 
-export function getLangFromUrl(url: URL): Lang {
-	const [, lang] = url.pathname.replace(import.meta.env.BASE_URL, '').split('/');
-	if (lang in LANGUAGES) {
-		return lang as Lang;
-	}
-	throw new Error(`Invalid language: ${lang}`);
-}
-
 export function useTranslate(lang: Lang): (...translations: string[]) => string {
 	return (...translations: string[]) => translations[LANGUAGES.indexOf(lang)]; ;
 }