feat: migrate deployment from ECS Fargate to AWS App Runner

[jfrench9]

Summary

This PR migrates our deployment infrastructure from ECS Fargate with Application Load Balancer to AWS App Runner, significantly simplifying our deployment architecture and reducing infrastructure complexity.

Key Changes

• Infrastructure Simplification: Removed complex ECS Fargate setup including ALB, target groups, security groups, and VPC configurations
• GitHub Actions Updates: Streamlined deployment workflows for staging and production environments to use App Runner deployment
• CloudFormation Optimization: Reduced CloudFormation template from ~960 lines to ~230 lines (-730 lines, 76% reduction)
• Documentation Updates: Updated README to reflect new App Runner deployment process

Benefits

• Simplified Operations: App Runner automatically handles load balancing, auto-scaling, and health checks
• Reduced Maintenance: Eliminates need to manage ALB, ECS clusters, and associated networking components
• Cost Optimization: Pay-per-use pricing model with automatic scaling to zero during low traffic
• Faster Deployments: Streamlined CI/CD pipeline with fewer infrastructure dependencies

Breaking Changes

⚠️ Infrastructure Changes Required:

• Existing ECS Fargate resources will be replaced with App Runner services
• Custom domain configuration may need to be updated
• Environment variables and secrets configuration has changed
• Load balancer endpoints will be replaced with App Runner URLs

Testing Notes for Reviewers

• Verify deployment workflows syntax in .github/workflows/
• Review CloudFormation template for proper App Runner service configuration
• Confirm environment variable mapping is correct
• Check that all necessary IAM permissions are included for App Runner
• Validate that health check endpoints are properly configured

Deployment Considerations

• This migration requires a blue-green deployment approach to avoid downtime
• DNS records will need to be updated to point to new App Runner endpoints
• Monitor application performance and scaling behavior after migration
• Backup strategy should be verified for the new architecture

Browser Compatibility

No browser compatibility changes - this is purely an infrastructure migration that maintains the same application functionality and endpoints.

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🤖 Generated with Claude Code

Branch Info:

• Source: refactor/app-runner-alb-replace
• Target: main
• Type: feature

Co-Authored-By: Claude noreply@anthropic.com