Economic indicators are this week expected to show signs of continued, if modest, progress in much of the world — all of which could be blown off course if the standoff between Greece and its lenders leads to a rupture in the euro zone. The currency bloc has been a millstone around the neck of the world economy since the financial crisis began and the ongoing drama surrounding Greece and its ability to repay its debts has added to that burden. Athens delayed a key debt payment to the International Monetary Fund on Friday, branding as “absurd” the terms of a proposed aid deal from lenders.