WASHINGTON — The longtime partner of a Capitol Police officer who died after the Jan. 6 attack sued former President Donald J. Trump and two Capitol rioters on Thursday, arguing that his death was a “direct and foreseeable consequence” of their roles in the mob violence that day. The suit, filed in Federal District Court for the District of Columbia just before the second anniversary of the attack, seeks at least $10 million in damages each from Mr. Trump and two men accused of assaulting the officer, Brian D. Sicknick, with chemical spray on Jan. 6, George Tanios and Julian...