fix: 退休检测改为按最新合同类型判断，排除劳务协议员工

detectRetirementRisks、updateEmployeesRetirementDays、日历退休日期查询
均改为 include 最新合同并在代码中判断 contractType，而非用 some 查询
（some 会匹配到历史 FIXED 合同导致劳务人员仍被检测）

backend/src/services/retirement.service.ts

@@ -236,19 +236,24 @@ export async function confirmRetirementPolicy(orgId: string, policyId: string):
 
 // 批量更新员工距退休天数（基于个人出生日期 individually 计算）
 export async function updateEmployeesRetirementDays(orgId: string): Promise<void> {
-  // 查询有正式劳动合同的员工
+  // 查询所有在职员工（含合同信息），在代码中按最新合同判断
   const employees = await prisma.employee.findMany({
-    where: {
-      orgId,
-      contracts: { some: { contractType: { in: ['FIXED', 'UNFIXED'] } } },
-    },
-    select: { id: true, birthDate: true, gender: true, femaleWorkerType: true },
+    where: { orgId, status: 'ACTIVE', birthDate: { not: null } },
+    include: { contracts: { orderBy: { createdAt: 'desc' }, take: 1 } },
   })
 
   for (const emp of employees) {
-    if (!emp.birthDate) continue
+    const latestContractType = emp.contracts[0]?.contractType
+    if (!latestContractType || !['FIXED', 'UNFIXED'].includes(latestContractType)) {
+      // 非正式劳动合同：清除退休天数
+      await prisma.employee.update({
+        where: { id: emp.id },
+        data: { retirementDaysLeft: null },
+      })
+      continue
+    }
     const gender = emp.gender || '男'
-    const daysLeft = calcRetirementDaysLeft(emp.birthDate, gender, emp.femaleWorkerType)
+    const daysLeft = calcRetirementDaysLeft(emp.birthDate!, gender, emp.femaleWorkerType)
     if (daysLeft !== null) {
       await prisma.employee.update({
         where: { id: emp.id },