The budget blueprint calls for legislation that would add roughly $3 trillion to the deficit over a decade while imposing deep cuts in spending on health care and food programs for low-income people. That would help pay for $4.5 trillion in tax cuts, a huge sum that Republican tax writers have nevertheless said will constrain their and Mr. Trump’s ambitions. It also calls for raising the debt limit, the statutory cap on what the government can borrow to finance its debt, by $4 trillion, a heavy lift among anti-spending conservatives.