End game on backend on 0 health

.gitlab-ci.yml

backend/package.json

backend/src/controllers/README.md

backend/src/controllers/gameController.ts

backend/src/controllers/highscoreController.ts

backend/src/controllers/lobbyController.ts

backend/src/controllers/userController.ts

backend/src/functions/README.md

backend/src/functions/checkProjectileHit.ts

backend/src/functions/disposeInactiveGames.ts

backend/src/functions/validateGameState.ts

backend/src/functions/validateGameStateJSON.ts

backend/src/gameHandler.ts

backend/src/interfaces/IGame.ts

backend/src/interfaces/ILobby.ts

backend/src/interfaces/IStats.ts

backend/src/models/Game.ts

backend/src/models/Stats.ts

backend/src/models/Terrain.ts

backend/src/routes/README.md