*** GAME END ***
Your economy produced: 439918 apples.
Deflation is easily combated by raising interest above the next expected deflation level so that saving money becomes more lucrative than spending it. Inflation is combated by lowering interest as soon as it rises above the interest level. I never went below 0.50% interest, never above 5.50%. This is easy, maybe I should apply for the job of central banker.
I'm not sure, however, it seems that the game does not have the element of borrowing / lending of money. I think the optimal strategy will be quite different than yours, when the economy has the loan component.