Add a "Revert" feature to undo unsuccessful refinements

I would love a "revert" feature, since each set of refinement instructions seems to build on the refinement instructions previously entered (re-entering a past good set of instructions doesn’t give the same output as it did the first time). When things don’t go as intended and a set of refinement instructions results worse output than the previous set, it would be good to be able to have them ignored rather than contributing in any manner to subsequent renders. Ideally, one could “revert” more than one set of instructions. Alternatively, providing a way to cancel all refinement instructions and start again with the original/initially-generated AI output would also be helpful.