PHOENIX — Young people may be in their voting era. But many don’t plan to cast their ballots for Kamala Harris — and Democrats in Arizona are warning it could hobble her here. Youth voters turned out in record numbers in Arizona in 2020, helping to flip the state blue for Joe Biden. But four years later, some Democratic strategists fear the inroads Donald Trump has made over the last four years with younger voters — particularly with young men and young Latinos — is eating away at one of the party’s core, but most fickle, constituencies. And while Harris…