Skyrocketing lumber prices threaten to thwart the momentum of the U.S. housing market, which for months has been one of the brightest stars of the recovery from the pandemic recession.  At the onset of the health crisis, "the mills stopped producing," said Dustin Jalbert, senior economist and lumber industry specialist at Fastmarkets in Burlington, Massachusetts. "As soon as they saw 20 million unemployed, they shut down production."  But COVID turned out to be a boon for the sector. Demand for low population density and home office space spiked, with historically low mortgage rates ...