President Biden in his budget this week staked out major economic battle lines with former President Donald J. Trump, the presumptive Republican presidential nominee. The proposal offers the nation a glimpse of the diverging directions that retirement programs, taxes, trade and energy policy could take depending on the outcome of the November election.During the past three years, Mr. Biden has enacted key pieces of legislation aimed at bolstering the green energy economy, making infrastructure investments and reinforcing America’s domestic supply chain with subsidies for microchips,…