Feature request: Rolling/Carryover budget

[bhuynhdev]

Prerequisites

• I have searched for existing issues that already include this feature request, without success.

Describe the Feature Request

I propose we add an option to choose between Fixed and Rolling when creating a budget.
Rolling budget: At the end of the month, if there is unspent money for a budget, add that to next month budget

Describe the Use Case

This can help a person put up a small amount every month to save up for big periodical spending like Christmas Gift or Health Emergency

Additional Information

No response