West Marin homeowners who operate Airbnbs and other short-term rentals must apply for licenses by July 1 or forfeit their ability to remain in business. That is the date that the county will implement its new S.T.R. regulations, which it approved last year after a two-year moratorium on new registrations that sought to ease impacts on workforce housing. There are currently 130 people on a waiting list who will replace owners who do not renew…