Update 0.2.0

The demo has just been updated to version v0.2.0, introducing two new tower types (Fire and Lightning), tweaked colors and visuals, and rebalancing across the board.

Full changes below:

• The colors and visual style has been updated
• Added a Fire Tower and related upgrades
• Added a Lightning Tower and related upgrades
• Rebalanced a number of upgrades, and added new ones to existing builds
• Arrow Towers will now avoid targetting enemies that are already about to be defeated
• Allow toggling between spent / total and unspent / total token displays, by clicking on the token list
• General performance improvements
• Upgraded the engine to Godot 4.5