It remains the mystery at the heart of Boeing Co.’s 737 Max crisis: how a company renowned for meticulous design made seemingly basic software mistakes leading to a pair of deadly crashes. Longtime Boeing engineers say the effort was complicated by a push to outsource work to lower-paid contractors.The Max softwareーplagued by issues that could keep the planes grounded months longer after U.S. regulators this week revealed a new flawーwas developed at a time Boeing was laying off experienced engin...