Teachers struggling to afford the high cost of housing caught a break Thursday, with the launch of a new initiative that could help many buy a home. Landed, a San Francisco-based startup that assists local teachers with their down payments, said it’s expanding its reach to San Jose — offering its services to about 10,000 educators in eight school districts. And by next month, the startup also plans to extend its reach to the East Bay, offering assistance to teachers in western Contra Costa County.