When you buy a baby crib, an infant car seat or a child’s toy, it ought to be safe. Too often it’s not. And the federal agency in charge of strengthening product safety in America is at risk of being seriously weakened. The Consumer Product Safety Commission (CPSC) is a small government agency that rarely gets much attention from Congress. That could change this week, however, when the Senate takes up President Bush’s nomination of Mary Sheila Gall to be chairman of the commission.