[Issue Report]: Wirt re-rolls when you leave town then restart app

DevilutionX version

1.5.5 and 1.6 (haven't checked other versions)

Describe

After talking to the devs I've been informed that this way of re-rolling Wirt's items isn't intended: https://github.com/diasurgical/DevilutionX/discussions/8672#discussioncomment-18122847

This is caused by the game only keeping BoyItem in memory, but not in the savefile, which causes him to generate the item every time you restart the game. It's not a problem if you don't leave the town, because then the same item is generated (because the random seed is only saved after leaving the town). If you do, however, also leave the town, Wirt generates a brand new item.

To Reproduce

1. Start or load a singleplayer game.
2. Go to Wirt and have a look at his item.
3. Go to the caves.
4. Save the game.
5. Restart the app.
6. Load the game.
7. Go to Wirt and have a look at his item again.
8. Notice he now has a different item.

Expected Behavior

Wirt should keep his item even after leaving town and restarting the app.