Roughly 1,200 first graders from a Brooklyn school district with the city’s highest proportion of Black students are seeing $1,000 added to their new college savings accounts, the result of donations from Bloomberg Philanthropies and a local foundation. The Save for College Program, a public-private partnership, will announce a $1 million investment Tuesday in the college and career plans for age-eligible students in School District 18, spanning from Canarsie to East Flatbush.