refactor(i18n): simplify language handling across components

use Astro.currentLocale as single source of truth for language
remove manual lang prop passing to components
components now read language from document lang attribute

src/components/Footer.tsx

@@ -1,12 +1,25 @@
 import { useTranslations, type Lang } from "@/i18n/utils";
 import { personalInfo } from "@/lib/data";
 import { motion } from "framer-motion";
+import { useState, useEffect } from "react";
+import { defaultLang } from "@/i18n/ui";
 
 interface FooterProps {
-  lang: Lang;
+  lang?: Lang;
 }
 
-export default function Footer({ lang }: FooterProps) {
+export default function Footer({ lang: propLang }: FooterProps) {
+  // 优先使用props传入的语言，如果没有则尝试从HTML lang属性获取
+  const [lang, setLang] = useState<Lang>(propLang || defaultLang);
+  
+  useEffect(() => {
+    // 在客户端运行时，从HTML lang属性获取当前语言
+    const htmlLang = document.documentElement.lang as Lang;
+    if (htmlLang && (!propLang || htmlLang !== lang)) {
+      setLang(htmlLang);
+    }
+  }, [propLang, lang]);
+
   const t = useTranslations(lang);
   return (
     <footer className="border-t border-purple-500/10 py-6 bg-gradient-to-b from-background to-muted/20 backdrop-blur-sm">