How to redirect to a Salesforce lightning record deatil page on click event in JS?

Hi,

TO navigate you do not need to create any custom Event "force:navigateToSObject " will do the trick.

var navEvt = $A.get("e.force:navigateToSObject");
    navEvt.setParams({
      "recordId": "Pass the Record Id of budget record Here",
      "slideDevName": "related"
    });
    navEvt.fire();

for more detail, you can refer https://developer.salesforce.com/docs/component-library/bundle/force:navigateToSObject/documentation