Just over a year ago, state and corporate executives were heralding what they said could be some 870 high-paying jobs at the Port of Coeymans that would involve assembling offshore wind turbine engines and blades built by GE Vernova and LM Wind Power. But last week, those jobs vanished — at least for now — before they were ever created. That’s because two major offshore wind farms that were going to use the port as a fabrication area canceled their plans.