Gold futures broke $4,000 per ounce for the first time this week — a historic high that, for some, signals more than market jitters. It may reflect a deeper collapse of confidence in the American-led global financial system. The precious metal has surged more than 50 percent since January, driven by a rare convergence of forces. Central banks continue stockpiling bullion. Investors are retreating from the U.S. dollar. Commodity analysts cite a rare convergence of forces: dovish monetary policy,