feat: Enhance Unity example with interactive rotating cube and UI improvements

This commit introduces an interactive rotating cube demo in the Unity example, featuring a customizable speed and direction. The UI has been revamped to include real-time feedback on rotation speed, last message received, and communication direction. Additionally, overlay controls for speed adjustment and axis selection have been added, improving user interaction and visual feedback. The README has been updated to reflect these new features and usage instructions.

Author: juicycleff