The New Jersey Schools Construction Corp. and the state attorney general are suing firms involved in its multibillion-dollar building program to recoup public costs incurred. Late last month, they filed suit against STV Architects Inc., Newark, and a subcontractor, seeking $3.5 million to repair alleged structural and design defects in a $22.2-million school project in Irvington. “The issue that is the subject of the lawsuit arose, and was resolved during construction,” says STV.  “When the facts are fully known, STV will did nothing wrong.” The state earlier sued units of Getty Oil for $885,000 in site cleanup costs.