fix: PC 端全站移动端响应式修复

Critical:
- header.tsx: 手机菜单按钮 flex-row→flex-col, 修复 w-full 溢出
- compare/page.tsx: 参数面板 grid-cols-3→grid-cols-1 sm:grid-cols-3

High:
- sandbox/page.tsx: header 区 flex-wrap + 模型选择器 w-48→w-40 sm:w-48
- member/page.tsx: 功能对比行 grid 布局替代 flex, 防溢出
- workshop/page.tsx: 编辑区 flex-col sm:flex-row + 按钮组 flex-wrap

Medium:
- analytics/page.tsx: domain name truncate
- skills/[id]: CTA 按钮 w-full sm:w-auto

frontend/src/app/learning/analytics/page.tsx

@@ -106,7 +106,7 @@ export default function LearningAnalyticsPage() {
               <div key={domain.id}>
                 <div className="flex items-center justify-between mb-1.5">
                   <div className="flex items-center gap-2">
-                    <span className="text-sm font-medium text-foreground">{domain.name}</span>
+                    <span className="text-sm font-medium text-foreground truncate min-w-0">{domain.name}</span>
                     {domain.weak && (
                       <span className="text-xs px-1.5 py-0.5 bg-amber-100 text-amber-700 rounded">待加强</span>
                     )}