fix: HR系统优化批次1 - P0/P1问题修复

P0-3: 修复合同状态判断逻辑，有合同记录但signDate为null时不再误判未签
P0-5: 修复参保城市默认北京问题，导入和预览均改为null
P0-11: 添加全局ErrorBoundary防止白屏，三处布局均包裹
P1-2: 合同附件改为可选，允许先保存再补充上传
P1-7.2: 排班弹窗增加员工搜索（姓名/部门）
P1-8.2: 加班费导入支持Excel(xlsx/xls)格式，兼容中英文列名
P1-9: 社保/公积金基数月度办理支持逐人修改，后端返回recordId

backend/src/routes/social.routes.ts

@@ -878,6 +878,7 @@ router.get('/monthly-changes', async (req: AuthRequest, res: Response, next: Nex
       const config = await getConfigForCity(r.city)
       const detail = config ? calcSocialDetail(r.base, config) : null
       return {
+        recordId: r.id,
         employeeId: r.employeeId,
         name: r.employee.name,
         department: r.employee.department,
@@ -948,6 +949,7 @@ router.get('/housing/monthly-changes', async (req: AuthRequest, res: Response, n
       const config = await getConfigForCity(r.city)
       const detail = config ? calcHousingDetail(r.base, config) : null
       return {
+        recordId: r.id,
         employeeId: r.employeeId,
         name: r.employee.name,
         department: r.employee.department,
@@ -1012,6 +1014,7 @@ router.get('/active-declaration', async (req: AuthRequest, res: Response, next:
       const config = await getConfigForCity(r.city)
       const detail = config ? calcSocialDetail(r.base, config) : null
       return {
+        recordId: r.id,
         employeeId: r.employeeId,
         name: r.employee.name,
         department: r.employee.department,
@@ -1073,6 +1076,7 @@ router.get('/housing/active-declaration', async (req: AuthRequest, res: Response
       const config = await getConfigForCity(r.city)
       const detail = config ? calcHousingDetail(r.base, config) : null
       return {
+        recordId: r.id,
         employeeId: r.employeeId,
         name: r.employee.name,
         department: r.employee.department,