ALEXIS AKWAGYIRAM TEARS fill Ephraim Osinboyejo's eyes as he recalls the idealism that drove thousands of Nigerians like him into the streets to campaign against police brutality - and the night he saw young activists gunned down. The 39-year-old businessman says he returned to Nigeria last year after two decades abroad because he wanted to help his country. When nationwide demonstrations began on October 8, he volunteered to manage logistics at the main protest site in Lagos. But what began as a largely peaceful movement, driven by young, tech-savvy activists who used social media to grab global attention, turned into…