Fuad Shukr, the top Hezbollah commander killed by Israel on Tuesday, was a founding member of the Iran-backed group who helped oversee its expansion from a shadowy Lebanese civil war militia to a major force in the Middle East. His killing is the heaviest blow to Hezbollah’s command since the 2008 assassination of Imad Mughniyeh by the US and Mossad, underlining the gravity of this week’s escalation in the conflict, which has been rumbling across region since the deadly Gaza war erupted. While the assassination of Hamas leader Ismail Haniyeh in Tehran marked a major political setback to the Pa…