修正中文页面切换回英文的语言切换逻辑

siteConfig.baseUrl 在非默认 locale 下已包含 locale 前缀，
需要先剥离 locale 再拼接路径。

Author: CodFrm

src/theme/Navbar/index.tsx

@@ -21,16 +21,17 @@ function Navbar(): React.ReactElement {
 
   const getAlternateLocalePath = useCallback(() => {
     const pathname = location.pathname;
-    const { baseUrl } = siteConfig;
+    // siteConfig.baseUrl includes locale for non-default locales (e.g. /docs/zh-CN/)
+    // Strip locale to get the bare base (e.g. /docs/)
+    const bareBase = siteConfig.baseUrl.replace(/zh-CN\/$/, "");
+    const pathAfterBare = pathname.slice(bareBase.length);
     if (currentLocale === "en") {
       // /docs/some-page -> /docs/zh-CN/some-page
-      const pathAfterBase = pathname.slice(baseUrl.length);
-      return `${baseUrl}zh-CN/${pathAfterBase}`;
+      return `${bareBase}zh-CN/${pathAfterBare}`;
     }
     // /docs/zh-CN/some-page -> /docs/some-page
-    const pathAfterBase = pathname.slice(baseUrl.length);
-    const withoutLocale = pathAfterBase.replace(/^zh-CN\/?/, "");
-    return `${baseUrl}${withoutLocale}`;
+    const withoutLocale = pathAfterBare.replace(/^zh-CN\/?/, "");
+    return `${bareBase}${withoutLocale}`;
   }, [currentLocale, location.pathname, siteConfig]);
 
   const toggleColorMode = useCallback(() => {