[Feature] Big Sale / Bonus Boost / Coupon

[gn01842919]

Feature Description:

Introduce the following item effects:

1. Big Sale

   • Using this item provides a specified discount on store purchases within a designated time period.

2. Experience/Gold Boost

   • Using this item grants bonus experience or rewards for completing tasks within a specified time frame.

The above effects are especially helpful during moments of low mood, when extra encouragement is needed, or during particularly lazy periods when motivation is lacking.

Add it is nice to have coupon as well:

1. Coupon
   • Using this item allows the purchase of one product at a discounted price.