By Laila Bassam, Nidal al-Mughrabi and Arafat Barbakh BEIRUT/CAIRO/GAZA (Reuters) -Israel killed Hamas deputy leader Saleh al-Arouri in a drone strike in Lebanon’s capital Beirut on Tuesday, Lebanese and Palestinian security sources said, raising the potential risk of war in Gaza spreading well beyond the Palestinian enclave. Arouri, 57, was the first senior Hamas political leader to be assassinated since Israel launched a shattering air and ground offensive against the group almost three months ago after its shock assault and rampage into Israeli towns. Lebanon’s heavily armed Hezbollah group…