Caroline Kennedy, the first daughter of Camelot, has decided to seek Hillary Rodham Clinton's U.S. Senate seat - a decision that rocks the landscape of the race to be appointed to succeed the outgoing senator. "She has decided she wants the Senate seat," a source close to Kennedy told The Post. She called Gov. Paterson today to let him know. The move makes official what some Kennedy family members had been urging her to do for weeks. Kennedy has already signed up powerhouse consulting firm Knickerbocker SKD, which advises Mayor Bloomberg - who sang her praises recently as a qualified...