ux: 统一PageGuide位置到页面最顶部 + 侧边栏不显示品牌名

- SalaryDashboard/ESign: PageGuide 从标题下方移到标题上方
- Termination: PageGuide 从列表视图块内移到页面顶部
- SocialInsurance/Dashboard/Attendance: 页面顶部新增总览 PageGuide
- 侧边栏左上角不再回退显示品牌名，仅显示企业名称

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

frontend/src/components/layout/SidebarNav.tsx

@@ -150,7 +150,7 @@ export default function SidebarNav({ mobileOpen, onClose }: { mobileOpen: boolea
         {/* Logo 区 */}
         <div className="h-14 flex items-center gap-2 px-4 border-b border-gray-200 shrink-0">
           <Logo className="w-5 h-5 text-primary" />
-          <span className="font-bold text-sm text-gray-900 truncate">{orgData?.name || '安职通'}</span>
+          <span className="font-bold text-sm text-gray-900 truncate">{orgData?.name || ''}</span>
         </div>
 
         {/* 导航菜单 */}