WASHINGTON, June 11 — Nancy Reagan started her seventh day of mourning Friday bowed over her husband's coffin in the Rotunda of the Capitol. By the time the sun set in California 12 hours later, Mrs. Reagan had attended a state funeral at National Cathedral, a formal send-off at Andrews Air Force Base and, after a cross-country flight aboard an Air Force jumbo jet, Ronald Reagan's burial on a hillside outside Los Angeles. For Mrs. Reagan, it was an exhausting and emotional test of endurance, all the more so for an 82-year-old woman who, as friends noted, for 10 years...