- Added new `thruster.mp3` asset and loaded it in **BootScene** (`sfx_thruster` key).
- Extended `Player` class:
* Created `thrusterSound` (looping) on construction.
* Play sound while thrust is active and stop when thrust ends.
* Ensure sound stops on player death and is destroyed on cleanup.
- Minor cleanup to stop thruster audio when the player entity is destroyed.
- Added new sound effect and music MP3 files to the project.
- Updated **BootScene** to preload all music tracks and sound effects.
- Implemented music playback:
* MenuScene now plays looping title music and stops it on shutdown.
* GameScene now stops any playing music on shutdown and starts level‑specific background music with fallback to the last track.
- Added SFX triggers for player shooting, alien shooting, missile launch, impacts, alien death, and player death.
- Cleaned up formatting and minor code style issues in GameScene (group/array declarations, tweens, UI text creation, level setup loops, etc.).
- Ensured proper cleanup of music objects when scenes change.
Brian Fertig