feat: 多语言将中文设置为默认的语言

src/i18n/locales.ts

@@ -26,6 +26,12 @@ export function isLang(value: string | undefined): value is Lang {
 export type RouteKey = '' | 'teaching-philosophy' | 'curriculum' | 'faculty' | 'about';
 
 export function hrefFor(lang: Lang, segment: RouteKey): string {
-  if (!segment) return `/${lang}`;
-  return `/${lang}/${segment}`;
+  const prefix = lang === DEFAULT_LANG ? '' : `/${lang}`;
+  if (!segment) return prefix || '/';
+  return `${prefix}/${segment}`;
+}
+
+/** 从 [...lang] rest 参数解析语言，undefined 时返回默认语言 */
+export function resolveLang(param: string | undefined): Lang {
+  return isLang(param) ? param : DEFAULT_LANG;
 }