Add an option to automatically Pause funding when Due Date is reached.
If we think of Goals as one-time expenses, having a default behavior of suspending funding at the Due Date would help clarify the difference between an Expense and a Goal.
At the due date, if the target amount is fulfilled and funding suspended, the Goal should be marked as "Fulfilled" and able to be spent from without triggering additional funding (unless the user manually reactivates funding).