[GAMEPLAY] Biscuits disable shop's undo feature

If you buy, sell or upgrade an item and a biscuit appears in your inventory (from the inspiration rune) you can no longer undo any changes.

To reproduce:

1. Take biscuit rune
2. Buy an item and leave fountain
3. Return to fountain and while still in fountain, make a change to your inventory (buy, sell or upgrade)
4. Wait for biscuit to appear in inventory (e.g. til 3:00 in-game time)
5. You can no longer undo your last action.

This will happen 100% of the time.

A simple fix would be for biscuits to check your location before being added to your inventory, in other words: add a biscuit to players inventory at 3, 6, 9, 12 minutes if they are outside of fountain, similar to how they aren't added until you have a free inventory slot.