fix: 实现中英文语言切换功能

- 新建 LocaleSwitcher 组件支持语言切换
- 使用 usePathname 保持当前页面路径
- 点击切换时自动更新 URL 语言前缀

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/app/[locale]/layout.tsx

@@ -1,6 +1,7 @@
 import { notFound } from "next/navigation"
 import { setRequestLocale } from 'next-intl/server'
 import Link from "next/link"
+import { LocaleSwitcher } from "@/components/locale/LocaleSwitcher"
 
 const locales = ['zh', 'en']
 
@@ -72,9 +73,7 @@ export default async function LocaleLayout({
 
             {/* Right side */}
             <div className="hidden md:flex items-center space-x-4">
-              <button className="font-display text-sm font-bold hover:opacity-70">
+              <LocaleSwitcher currentLocale={locale} />
-                中文 / EN
-              </button>
               <Link
                 className="bg-white dark:bg-surface-dark border-2 border-black dark:border-white px-4 py-2 font-display text-sm font-bold shadow-neo-sm hover:shadow-none hover:translate-x-[2px] hover:translate-y-[2px] transition-all"
                 href="#"

src/components/locale/LocaleSwitcher.tsx

@@ -0,0 +1,41 @@
+'use client'
+
+import { usePathname } from 'next/navigation'
+import Link from 'next/link'
+
+const locales = ['zh', 'en'] as const
+const localeNames: Record<string, string> = {
+  zh: '中文',
+  en: 'EN'
+}
+
+export function LocaleSwitcher({ currentLocale }: { currentLocale: string }) {
+  const pathname = usePathname()
+
+  // 移除当前语言前缀，获取基础路径
+  const getBasePathname = () => {
+    const segments = pathname.split('/').filter(Boolean)
+    if (segments[0] && locales.includes(segments[0] as any)) {
+      return '/' + segments.slice(1).join('/')
+    }
+    return pathname
+  }
+
+  const basePathname = getBasePathname()
+
+  const switchLocale = (newLocale: string) => {
+    // 切换到另一种语言
+    return `/${newLocale}${basePathname}`
+  }
+
+  const otherLocale = currentLocale === 'zh' ? 'en' : 'zh'
+
+  return (
+    <Link
+      href={switchLocale(otherLocale)}
+      className="font-display text-sm font-bold hover:opacity-70 transition-opacity"
+    >
+      {localeNames[currentLocale]} / {localeNames[otherLocale]}
+    </Link>
+  )
+}