EGYPTCairo — Egypt’s military moved swiftly Thursday against senior figures of the Muslim Brotherhood, targeting the backbone of support for ousted President Mohammed Morsi. In the most dramatic step, authorities arrested the group’s revered leader from a seaside villa and flew him by helicopter to detention in the capital. With a top judge newly sworn in as interim president to replace Morsi, the crackdown poses an immediate test to the new army-backed leadership’s promises to guide Egypt to democracy: The question of how to include the 83-year-old fundamentalist group. That question has long been at the heart of democracy efforts in Egypt. Hosni Mubarak and previous authoritarian regimes banned the group, raising cries even from pro-reform Brotherhood critics that it must be allowed to participate if Egypt was to be free. Now the Brotherhood is reeling under a huge backlash from a public that says the group and its Islamist allies abused their electoral mandate.