ATHENS — Greece entered an even more volatile phase of its financial crisis Sunday as official projections forecast a resounding win for the “no” campaign in a referendum that could decide the country’s financial fate in the short term and its role in Europe in the long term. The vote, on a proposed bailout deal from Athens’ international lenders, was a strong rebuke to European Union leaders who had warned that the referendum was, in effect, a vote on whether Greece wanted to keep on using the euro as its currency. Because of the convoluted ballot question, and the competing claims over its implications, many Greeks complained of confusion over just what was being asked of them. Maria Liapi, who helped campaign for the “no” side, said she wanted to reject a bailout agreement that would bring more hardship to Greece, whose economy has contracted by more than 25 percent since the country began accepting rescue loans in 2010 and implementing harsh spending cuts in return.