WTI crude oil posted a volatile and ultimately lower week as a record U.S. inventory build collided with an evolving diplomatic effort between Washington and Tehran. The April contract touched a seven-month high of $67.28 on Monday before reversing sharply, finishing near $65.31 by Thursday night, down $1.17 or 1.76% on the week. Iran-U.S. Negotiations: From War Premium to Cautious Optimism The dominant theme all week was the diplomatic standoff over Iran's nuclear program. Early in the week, crude was underpinned by a significant geopolitical…