When nations exchange fire across contested borders, the tremors reach far beyond the battlefield — they travel through pipelines, across shipping lanes, and into the calculations of every investor who understands that oil remains the circulatory fluid of the modern world. On Monday, fresh military hostilities between the United States and Iran pushed Brent crude past $90 a barrel, reminding markets that the Strait of Hormuz — through which a fifth of the world's traded oil flows daily — is never far from the edge of disruption. Energy companies from ExxonMobil to SLB rose sharply as investors