Changelog

1.0.0

Initial release
Register upgrade trees with UpgradeAPI.RegisterTree()
Add nodes to existing trees with UpgradeAPI.RegisterInTree()
Query purchase state with UpgradeAPI.IsPurchased() and UpgradeAPI.CanPurchase()
Support for Money and Research cost types
Automatic per-slot save/load persistence
Property inheritance (icons, colors, cost type) from parent to child nodes
Vanilla icon matching via VanillaIconMatch
OnPurchased callbacks fire on purchase and on game load