chore(docker): remove container_name and network, add healthcheck

- Remove explicit container_name to allow Docker Compose to generate unique names
- Remove custom network configuration as default network is sufficient
- Add curl installation and healthcheck to Dockerfile for better container monitoring

calorie_tracker_app/Dockerfile

@@ -8,6 +8,9 @@ ENV PYTHONUNBUFFERED=1
 ENV FLASK_APP=app.py
 
 # Install dependencies
+# Install curl for healthcheck
+RUN apt-get update && apt-get install -y curl && rm -rf /var/lib/apt/lists/*
+
 COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 
@@ -24,5 +27,9 @@ RUN sed -i 's/\r$//' entrypoint.sh && \
 # Expose port (default 5000)
 EXPOSE 5000
 
+# Healthcheck
+HEALTHCHECK --interval=30s --timeout=3s \
+  CMD curl -f http://localhost:5000/ || exit 1
+
 # Use entrypoint script to init db, seed data, and start server
 ENTRYPOINT ["./entrypoint.sh"]