feat(i18n): implement astro i18n integration and refactor locale handling

- Add i18n configuration to astro.config.mjs with default locale and routing
- Refactor language handling to use Astro.currentLocale instead of URL parsing
- Update tsconfig to include only necessary files for better type checking
- Improve LanguageSwitcher to handle routing based on astro i18n config
- Add new translation keys and update components to use dynamic titles
- Simplify MotionWrapper component by removing unused default animations

src/pages/zh/index.astro

@@ -1,17 +1,21 @@
 ---
-import { getLangFromUrl } from "@/i18n/utils";
 import Layout from "@/layouts/Layout.astro";
-import GlassHeader from "@/components/GlassHeader";
-import HeroSection from "@/components/HeroSection";
-import ExperienceSection from "@/components/ExperienceSection";
-import SkillsSection from "@/components/SkillsSection";
-import ProjectsSection from "@/components/ProjectsSection";
-import Footer from "@/components/Footer";
+import GlassHeader from "@/components/GlassHeader.tsx";
+import HeroSection from "@/components/HeroSection.tsx";
+import ExperienceSection from "@/components/ExperienceSection.tsx";
+import SkillsSection from "@/components/SkillsSection.tsx";
+import ProjectsSection from "@/components/ProjectsSection.tsx";
+import Footer from "@/components/Footer.tsx";
+import { useTranslations } from "@/i18n/utils";
 
-const lang = getLangFromUrl(Astro.url);
+// For /zh/ pages, Astro.currentLocale should be 'zh'.
+// We explicitly set lang to 'zh' to ensure type correctness and intent.
+const lang: "en" | "zh" = 'zh';
+const t = useTranslations(lang);
+const pageTitle = t('page.home.title');
 ---
 
-<Layout title="首页" lang={lang}>
+<Layout title={pageTitle}>
   <GlassHeader lang={lang} client:only="react" />
   <main class="min-h-screen">
     <HeroSection lang={lang} client:only="react" />
@@ -19,5 +23,5 @@ const lang = getLangFromUrl(Astro.url);
     <SkillsSection lang={lang} client:only="react" />
     <ProjectsSection lang={lang} client:only="react" />
   </main>
-  <Footer lang={lang} client:only="react" />
+  <Footer lang={lang} client:load />
 </Layout>