feat: 商业保险/员工福利独立页面+易签宝电子签署框架

- 商业保险：从社公商保中拆出为独立页面，侧边栏新增「福利保障」分组
- 员工福利：新建完整模块（方案管理+批量参保+员工汇总），Prisma模型+后端路由+前端页面
- 电子签署：搭建易签宝对接框架（ESignRecord模型+创建/查询/取消/回调接口+前端签署管理页面）
- 侧边栏新增「福利保障」分组：商业保险、员工福利、电子签署
- Prisma schema 新增6个模型：CommercialInsurancePlan/Enrollment, EmployeeBenefitPlan/Enrollment, ESignRecord

frontend/src/pages/SocialInsurance.tsx

@@ -11,7 +11,6 @@ import Button from '../components/ui/Button'
 import { Input, Label } from '../components/ui/Input'
 import { MonthlyRow, MonthlyHousingRow } from './social-insurance/MonthlyRows'
 import SpecialDeductionTab from './social-insurance/SpecialDeductionTab'
-import CommercialInsuranceTab from './social-insurance/CommercialInsuranceTab'
 
 // 金额格式化：保留两位小数 + 千分位
 const fmt = (n: number) => (n || 0).toLocaleString('zh-CN', { minimumFractionDigits: 2, maximumFractionDigits: 2 })
@@ -19,7 +18,7 @@ const fmt = (n: number) => (n || 0).toLocaleString('zh-CN', { minimumFractionDig
 export default function SocialInsurance() {
   const queryClient = useQueryClient()
   const confirm = useConfirm()
-  const [tab, setTab] = useState<'monthly' | 'social' | 'housing' | 'deduction' | 'commercial'>('monthly')
+  const [tab, setTab] = useState<'monthly' | 'social' | 'housing' | 'deduction'>('monthly')
   const [city, setCity] = useState<string>('北京')
   const [showAddCity, setShowAddCity] = useState(false)
   const [newCityName, setNewCityName] = useState('')
@@ -367,7 +366,7 @@ export default function SocialInsurance() {
 
       {/* Tab 切换 + 城市选择 */}
       <div className="flex items-center gap-4 border-b">
-        {(['monthly', 'social', 'housing', 'deduction', 'commercial'] as const).map((t) => (
+        {(['monthly', 'social', 'housing', 'deduction'] as const).map((t) => (
           <button
             key={t}
             className={`px-4 py-2 text-sm font-medium border-b-2 transition-colors ${
@@ -375,7 +374,7 @@ export default function SocialInsurance() {
             }`}
             onClick={() => { setTab(t); setShowVersions(false); setShowNewVersion(false); setShowAdjust(false); setAdjustData(null); setEditItems({}); setEditingId(null); setMonthlyProcessed(false); setProcessStatus(null) }}
           >
-            {t === 'monthly' ? '月度办理' : t === 'social' ? '社保' : t === 'housing' ? '公积金' : t === 'deduction' ? '专项附加扣除' : '商险管理'}
+            {t === 'monthly' ? '月度办理' : t === 'social' ? '社保' : t === 'housing' ? '公积金' : '专项附加扣除'}
           </button>
         ))}
         {(tab === 'social' || tab === 'housing') && (
@@ -1148,11 +1147,6 @@ export default function SocialInsurance() {
         <SpecialDeductionTab month={deductionMonth} setMonth={setDeductionMonth} />
       )}
 
-      {/* ========== 商险管理 Tab ========== */}
-      <div className={tab === 'commercial' ? '' : 'hidden'}>
-        <CommercialInsuranceTab />
-      </div>
-
     </div>
   )
 }