chore: remove Docker and containerization configuration files

The project no longer requires containerized deployment. Removing nixpacks.toml, Dockerfile, and docker-compose.yml simplifies the repository and aligns with a shift to a different hosting or deployment strategy.

docker-compose.yml

@@ -1,24 +0,0 @@
-version: '3.8'
-
-services:
-  app:
-    build: .
-    ports:
-      - "5000:5000"
-    volumes:
-      - calorie_tracker_data:/app/data
-    environment:
-      - PORT=5000
-      - NODE_ENV=production
-      # Add other environment variables here or use an env_file
-      # - API_NINJAS_KEY=your_key_here
-      # - SECRET_KEY=your_secret_here
-    restart: always
-    healthcheck:
-      test: ["CMD", "curl", "-f", "http://localhost:5000/"]
-      interval: 30s
-      timeout: 10s
-      retries: 3
-
-volumes:
-  calorie_tracker_data: