House and Senate negotiators announced this afternoon that they had reached agreement on a $789 billion economic stimulus bill, clearing the way for final Congressional action and President Obama’s signature. “The differences between the House and Senate versions, we’ve resolved,” Senator Harry Reid of Nevada, the Democratic majority leader, said in a Capitol news conference. The differences were resolved by a lot of intense “give and take,” Mr. Reid said, “and if you don’t mind my saying so, that’s an understatement.” Senator Susan Collins of Maine, a centrist Republican whose support was crucial to the outcome, said the final package includes $150 billion in spending on infrastructure, including transportation facilities, and considerable tax relief. Moreover, she said, it includes significant money to aid state governments. Despite intense lobbying by governors, the final deal slashed $35 billion from a proposed state fiscal stabilization fund, eliminated $16 billion in aid for scho