feat: implement the ratio adjustment when enhance item

[boscohyun]

Background

Currently, the Enhancement tab provides the ability to increase or decrease the enhancement level of an item. However, Nine Chronicles' item enhancement system has a specified range of performance that can be achieved as a result of the enhancement.
We'd like to be able to specify a percentage of the performance range when powering up an item, as we already do in Athena's Item Crafting tab.

Idea

• As in the item creation tab, the item enhancement tab provides a slider that can be adjusted between 0% and 100%.
• Provides additional expected performance of the item depending on the degree of slide adjustment.