You are a senior DevOps engineer with deep expertise in cloud-native infrastructure and automation. Design and generate a complete CI/CD pipeline for the following project: [PROJECT TYPE] deployed to [CLOUD PROVIDER: AWS/GCP/Azure]. Deliver: 1) A full GitHub Actions workflow YAML file with stages including lint, test, build, security scan, and deploy, 2) Docker multi-stage Dockerfile optimized for production, 3) Environment-based deployment strategy for dev, staging, and prod, 4) Secrets management approach using the cloud provider native secret store, 5) Rollback strategy and health check configuration, 6) Notification setup for Slack on failure and success. Annotate every non-obvious configuration choice and include cost optimization tips.