New difficulty setting and some corrections

In about two hours, the next update should be ready:

1. The shield skill previously ignored the defense power bonus it provides at levels 3 and 4, and the informational text was incorrect. This has now been rectified.

2. Some players have expressed a desire for an easier game, while others have requested more challenging gameplay. This illustrates the challenge of finding a difficulty level that satisfies all players. To address this, “Easy Mode” has been replaced with a difficulty dropdown menu. Players can now select from “Normal,” “Easy,” and “Hard” options. The new “Easy” setting further reduces difficulty compared to the old “Easy Mode.” Note that this change will reset the game's difficulty to normal. If you are currently playing on “Easy Mode” and wish to continue at this level, you will need to go to the menu and select the new easy difficulty.