- Added `scaleIncomingEnemyDamage` method to `Difficulty` enum for handling damage scaling based on difficulty level.
- Introduced `lives` attribute to `Player` class with methods to manage lives.
- Updated enemy classes (`Dog`, `Guard`, `Mutant`, `Officer`, `SS`, `HansGrosse`) to utilize difficulty settings for health and damage calculations.
- Modified enemy drop logic to reflect new collectible types and behaviors.
- Created tests for verifying enemy drop parity, collectible values, and difficulty damage scaling.
- Adjusted enemy spawn logic to ensure standing enemies remain idle until alerted.
- Enhanced scoring system to reflect updated score values for different enemy types.
Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>