feat: 调部门改为调动，使用组织架构部门和职务下拉选择

- 后端：EmployeeDepartmentRecord 增加 oldPosition/newPosition 字段
- 后端：department-change 接口支持 departmentId 关联 + position 职务变动
- 后端：同步更新 Employee.departmentId 和 Employee.position
- 前端：DeptChangeModal 改为从组织架构下拉选择目标部门（树形）和职务
- 前端：选择部门后自动过滤该部门下的职务
- 前端：按钮文案从"调部门"改为"调动"

Generated with [Devin](https://devin.ai)

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

backend/src/routes/roster.routes.ts

@@ -1442,10 +1442,10 @@ router.get('/:id/salary-records', authMiddleware, async (req: AuthRequest, res,
   } catch (err) { next(err) }
 })
 
-// 调部门
+// 调动（部门+职务变动）
 router.post('/:id/department-change', authMiddleware, async (req: AuthRequest, res, next) => {
   try {
-    const { newDepartment, effectiveMonth, reason } = req.body
+    const { newDepartment, newPosition, departmentId, effectiveMonth, reason } = req.body
     const employee = await prisma.employee.findFirst({
       where: { id: req.params.id, orgId: req.user!.orgId },
     })
@@ -1454,22 +1454,35 @@ router.post('/:id/department-change', authMiddleware, async (req: AuthRequest, r
     }
 
     const oldDepartment = employee.department
+    const oldPosition = employee.position || null
     const effMonth = effectiveMonth || dateToMonth(new Date())
     const prevEffMonth = prevMonth(effMonth)
 
+    // 校验 departmentId 是否属于当前组织
+    let deptName = newDepartment
+    if (departmentId) {
+      const dept = await prisma.department.findFirst({ where: { id: departmentId, orgId: req.user!.orgId } })
+      if (!dept) {
+        return res.status(400).json({ success: false, error: { code: 'VALIDATION_ERROR', message: '目标部门不存在' } })
+      }
+      deptName = dept.name
+    }
+
     // 关闭之前有效记录
     await prisma.employeeDepartmentRecord.updateMany({
       where: { employeeId: req.params.id, endMonth: null },
       data: { endMonth: prevEffMonth },
     })
 
-    // 创建新部门记录
+    // 创建新调动记录
     const record = await prisma.employeeDepartmentRecord.create({
       data: {
         orgId: req.user!.orgId,
         employeeId: req.params.id,
         oldDepartment,
-        newDepartment,
+        newDepartment: deptName,
+        oldPosition,
+        newPosition: newPosition || null,
         effectiveMonth: effMonth,
         endMonth: null,
         changeType: 'TRANSFER',
@@ -1478,13 +1491,17 @@ router.post('/:id/department-change', authMiddleware, async (req: AuthRequest, r
       },
     })
 
-    // 同步 Employee 便捷字段
+    // 同步 Employee 字段（department 文本 + departmentId 关联 + position 职务）
     await prisma.employee.update({
       where: { id: req.params.id },
-      data: { department: newDepartment },
+      data: {
+        department: deptName,
+        departmentId: departmentId || null,
+        position: newPosition || employee.position,
+      },
     })
 
-    await auditLog(req, 'CREATE', 'DEPARTMENT_CHANGE', record.id, { employeeId: req.params.id, oldDepartment, newDepartment })
+    await auditLog(req, 'CREATE', 'DEPARTMENT_CHANGE', record.id, { employeeId: req.params.id, oldDepartment, newDepartment: deptName, oldPosition, newPosition })
     res.json({ success: true, data: record })
   } catch (err) { next(err) }
 })