fix: 修复增量同步时软删除用户导致的重复username错误

backend/app/services/employee_sync_service.py

@@ -246,15 +246,23 @@ class EmployeeSyncService:
             logger.warning(f"员工 {full_name} 没有手机号，跳过")
             return None
         
-        # 检查用户是否已存在（通过手机号）
-        stmt = select(User).where(
-            User.phone == phone,
-            User.is_deleted == False
-        )
+        # 检查用户是否已存在（通过手机号，包括已软删除的）
+        stmt = select(User).where(User.phone == phone)
         result = await self.db.execute(stmt)
         existing_user = result.scalar_one_or_none()
         
         if existing_user:
+            # 如果是软删除用户，恢复它
+            if existing_user.is_deleted:
+                existing_user.is_deleted = False
+                existing_user.full_name = full_name or existing_user.full_name
+                existing_user.is_active = True
+                dingtalk_id = employee_data.get('dingtalk_id')
+                if dingtalk_id:
+                    existing_user.dingtalk_id = dingtalk_id
+                logger.info(f"恢复软删除用户: {phone} ({full_name})")
+                return existing_user
+            
             # 如果用户已存在但没有dingtalk_id，则更新
             dingtalk_id = employee_data.get('dingtalk_id')
             if dingtalk_id and not existing_user.dingtalk_id: