BROOKLYN - Nearly 700 public school workers are joining the ranks of the unemployed as city officials hand out pink slips. Teachers were mostly spared in the latest round of cuts, but hundreds of aides, parent coordinators and other support staffers have been laid off. The move comes as one of the largest single-agency layoffs of Mayor Michael Bloomberg's administration.The mayor blames the cuts on stubborn union leadership. School worker unions, meanwhile, say the cuts will hurt the most in struggling, low-income communities.