* Spent career as Treasury official, central banker * As ECB chief, guided euro zone through debt crisis * Now faces tumult of Italian party politics ROME, Feb 3 (Reuters) - Mario Draghi has never shirked a challenge, from salvaging the reputation of Italy’s central bank to saving the euro. He is about to take on what may be an even tougher task. Little over a year after leaving the presidency of the Frankfurt-based European Central Bank, Draghi, 73, was asked by Italy’s head of state on Wednesday to resolve political chaos in Rome and form the country’s 67th post-war government. For th...