fix: yonan npc now can exchange items

[lamonato29]

Description

Add the possibility of exchanging items with the npc

Behaviour

Actual

Currently, the functionality to exchange items for a mount item is missing

Expected

Exchange the items Blue and Golden Cordon, Golden Bijou, Sun Medal anda Sunray Emblem for a Regalia of Suon (mount item).

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested

Tested in the game and it is working.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I checked the PR checks reports
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works