TALLAHASSEE — Abortion rights advocates spent months, and millions of dollars, gathering petition signatures so Florida voters could decide if they want abortion to be protected now that Roe v. Wade has been overturned. They got the measure on the Nov. 5 ballot, and hundreds of thousands of Floridians voting by mail already have said yes or no to Amendment 4, the abortion question. But an 11th-hour lawsuit filed Wednesday by anti-abortion opponents threatens to derail their efforts.