U.S.-Iran ceasefire deal dampens demand for safe-haven greenback Currencies mostly rangebound; yen remains in intervention zone Fed seen holding rates steady but board may lean more hawkish SINGAPORE, June 17 (Reuters) - The dollar eased slightly on Wednesday ahead of the Federal Reserve's first policy decision under chair Kevin Warsh, with lingering optimism over an interim U.S.-Iran peace deal underpinning risk appetite and dampening demand for the safe-haven currency.