Huawei Technologies Co. added a thin new handset to its lineup, marking the Chinese tech champion’s most direct response to Apple Inc.’s iPhone Air.The new Huawei Mate 70 Air measures 6.6mm thick and costs 4,199 yuan ($590), significantly undercutting the $999 iPhone Air on price but failing to match its extreme thinness. Apple introduced the Air branding to its smartphone lineup for the first time with the new phone launched alongside its iPhone 17 generation this fall — and Huawei is openly go...