BEIJING — China’s industrial firms reported stronger profit growth early in the year, reinforcing recovery signals in the world’s second-largest economy even as the Middle East war threatens global growth. Business margins remain squeezed as rising input costs and fierce competition bite across sectors, while trade and geopolitical tensions cloud the outlook for exports a key engine of economic growth.Industrial profits grew 15.2 percent in the first two months over the same period last year, following a 0.6-percent increase for the whole of last year, data from the National Bureau of Statistics showed on Friday. Among the sectors reporting the…