American forces have routed Al Qaeda in Mesopotamia, the Iraqi militant network, from every neighborhood of Baghdad, a top American general said today, allowing American troops involved in the “surge” to depart as planned. Maj. Gen. Joseph F. Fil Jr., commander of United States forces in Baghdad, also said that American troops had yet to clear some 13 percent of the city, including Sadr City and several other areas controlled by Shiite militias. But, he said, “there’s just no question” that violence had declined since a spike in June.