The nameless workers who toil on the factory floor year after year. Playwright Dominique Morisseau puts them front and center in “Skeleton Crew,” now at Broadway’s Samuel J. Friedman Theatre, presented by the Manhattan Theatre Club. It’s the winter of 2008 and workers at a metal stamping factory in Detroit, Michigan wonder if the plant may shut down for good. People are being laid off with increasing frequency, with those remaining pushed ever harder to maintain work quotas. Rumors of a closing are ever-present, with continual instances of theft and sabotage on the assembly lines only adding to the already-existing tension. The story focuses on four factory personnel, all bound together by the need to keep their jobs. Faye (Phylicia Rashad), the worker’s union representative, is approaching her 30th year at the plant. Well aware of the difference between a severance package of 29 years and one of 30, it’s a …