feat: Phase 1-3 全部完成 — 沙盒增强、学情分析、学习路径

frontend/src/components/ui/theme-toggle.tsx

@@ -0,0 +1,22 @@
+'use client'
+
+import { Moon, Sun } from 'lucide-react'
+import { useTheme } from 'next-themes'
+import { Button } from '@/components/ui/button'
+
+export function ThemeToggle() {
+  const { theme, setTheme } = useTheme()
+
+  return (
+    <Button
+      variant="ghost"
+      size="icon"
+      onClick={() => setTheme(theme === 'dark' ? 'light' : 'dark')}
+      className="rounded-full"
+    >
+      <Sun className="h-[1.2rem] w-[1.2rem] rotate-0 scale-100 transition-all dark:-rotate-90 dark:scale-0" />
+      <Moon className="absolute h-[1.2rem] w-[1.2rem] rotate-90 scale-0 transition-all dark:rotate-0 dark:scale-100" />
+      <span className="sr-only">切换主题</span>
+    </Button>
+  )
+}