Deal Details Startup: CodeCombat Security type: Preferred equity Valuation: $25 million Share price: $1.71 Stage: Series A Minimum investment: $500 Where to invest: SeedInvest Deadline: August 7. (But campaign may end earlier if maximum target is reached.)   CodeCombat made more than $2 million last year teaching kids how to code. Its impressive traction is hard-earned. Nick Winter founded the company back in 2013. And he’s slowly built it…