fix(Feed): 修复countOf函数中乘数应用的逻辑错误

当基础值为正数时使用乘法，为负数时使用除法，确保计算结果的正确性

scripts/Structs/Feed.gd

@@ -72,7 +72,8 @@ func apply(entity: EntityBase):
 	selected.emit(allHave)
 	return allHave
 func countOf(index: int) -> int:
-	return ceil(costCounts[index] * multipiler())
+	var base = costCounts[index]
+	return ceil(base * multipiler()) if base > 0 else floor(base / multipiler())
 func multipiler() -> float:
 	if is_instance_valid(UIState.player):
 		return 1 - UIState.player.fields.get(FieldStore.Entity.PRICE_REDUCTION)