Export fallback language tag ("en") as a constant

src/login/i18n/index.ts

@@ -2,4 +2,3 @@ import type { GenericI18n, MessageKey, KcContextLike } from "./i18n";
 export type { MessageKey, KcContextLike };
 export type I18n = GenericI18n<MessageKey>;
 export { createUseI18n } from "./useI18n";
-export { fallbackLanguageTag } from "./i18n";