This commit introduces a complete tower management system including:
- Added TowerManager class to handle tower creation, updates, and firing logic
- Implemented gun tower configuration with damage, rate, duration, and range stats
- Created visual range circles for towers
- Integrated tower placement in level1 scene
- Added basic enemy detection and firing mechanics
- Updated wave manager to support level completion state
The changes enable the core tower defense functionality where towers automatically detect enemies in range and fire at them based on configured rates.