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/lib/api-services.ts

@@ -572,6 +572,42 @@ export const commercialInsuranceApi = {
   /** 删除方案 */
   removePlan: (id: string) =>
     del(`/commercial-insurance/plans/${id}`),
+  /** 批量参保 */
+  enroll: (planId: string, data: { employeeIds: string[]; premium?: number; effectiveFrom?: string }) =>
+    post(`/commercial-insurance/plans/${planId}/enroll`, data),
+  /** 退保 */
+  terminateEnrollment: (enrollmentId: string, effectiveTo?: string) =>
+    post(`/commercial-insurance/enrollments/${enrollmentId}/terminate`, { effectiveTo }),
+}
+
+// ========== 员工福利 ==========
+export const benefitApi = {
+  plans: () =>
+    get('/benefits/plans').then(unwrap<any[]>()),
+  savePlan: (data: Record<string, unknown>, editId?: string) =>
+    editId ? put(`/benefits/plans/${editId}`, data) : post('/benefits/plans', data),
+  removePlan: (id: string) =>
+    del(`/benefits/plans/${id}`),
+  enrollments: (planId: string) =>
+    get(`/benefits/plans/${planId}/enrollments`).then(unwrap<any[]>()),
+  enroll: (planId: string, data: { employeeIds: string[]; effectiveFrom?: string }) =>
+    post(`/benefits/plans/${planId}/enroll`, data),
+  terminateEnrollment: (enrollmentId: string, effectiveTo?: string) =>
+    post(`/benefits/enrollments/${enrollmentId}/terminate`, { effectiveTo }),
+  employeeSummary: () =>
+    get('/benefits/employee-summary').then(unwrap<any[]>()),
+}
+
+// ========== 电子签署（易签宝） ==========
+export const esignApi = {
+  list: (status?: string) =>
+    get('/esign', { params: status ? { status } : {} }).then(unwrap<any[]>()),
+  create: (data: { contractId?: string; employeeId: string; documentTitle: string; documentContent?: string; remark?: string }) =>
+    post('/esign/create', data),
+  status: (id: string) =>
+    get(`/esign/${id}/status`).then(unwrap<any>()),
+  cancel: (id: string) =>
+    post(`/esign/${id}/cancel`),
 }
 
 // ========== 离职相关 ==========