OS ANGELES - The Celtics and Lakers both pleaded their cases after the final buzzer Tuesday night. ''Game over. Our win,'' shouted the Boston players over premature victory cheers from a sellout crowd at Staples Center. ''Game over. Our win,'' cried the Lakers. Paul Pierce said it was ''like we were in court,'' though the chaotic scene that lasted a good two minutes resembled ''The Jerry Springer Show'' more than ''Judge Judy''.