feat: add language switcher component and update layout

- Introduced a new LanguageSwitcher component to facilitate language switching in the application.
- Added an SVG icon for the language switcher button.
- Updated the Header component to adjust margin for better spacing.
- Modified the Navigation component's margin and top properties for improved layout.
- Adjusted the ThemeToggle button size for consistency with the new design.

src/components/LanguageSwitcher.astro

@@ -0,0 +1,60 @@
+---
+import themeConfig from '@/config'
+
+const langs = ['', ...themeConfig.global.moreLocale]
+---
+
+<script is:inline define:vars={{ langs }}>
+ const langSwitch = document.getElementById('language-switcher')
+
+ langSwitch?.addEventListener('click', () => {
+   const { pathname, search, hash } = window.location
+
+   // 获取当前语言和路径段
+   const segments = pathname.split('/').filter(Boolean)
+   const firstSegment = segments[0] || ''
+   const currentLang = langs.includes(firstSegment) ? firstSegment : ''
+
+   // 获取下一个语言
+   const currentIndex = langs.indexOf(currentLang)
+   const nextLang = langs[(currentIndex + 1) % langs.length]
+
+   // 构建新的 URL
+   let newPath
+   if (currentLang) {
+     // 如果当前有语言前缀，替换它
+     segments[0] = nextLang || segments[0]
+     newPath = nextLang ? `/${segments.join('/')}` : `/${segments.slice(1).join('/')}`
+   }
+ else {
+     // 如果当前没有语言前缀
+     newPath = nextLang ? `/${nextLang}${pathname}` : pathname
+   }
+
+   // 确保路径至少是 "/"
+   newPath = newPath || '/'
+
+   // 切换语言
+   window.location.href = `${newPath}${search}${hash}`
+ })
+</script>
+
+<button
+  id="language-switcher"
+  class="absolute right-25.6 top-19.4 z-999 aspect-square w-7 c-secondary active:scale-92"
+  aria-label="Language Switch Button"
+  title="Language Switch Button"
+>
+  <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" class="h-full w-full">
+    <path d="M19 21 12.3 2h-1L4.7 21l-2.5.2v.8h6.3v-.8L5.7 21l2-5.9h7.5l2 5.9-3.3.2v.8h7.9v-.8zM8 14.3l3.4-10.1 3.5 10.1z" fill="currentColor" />
+  </svg>
+</button>
+
+<style>
+  #language-switcher {
+    transition: transform 0.3s ease;
+  }
+  #language-switcher:hover {
+    transform: scale(1.1);
+  }
+</style>