Feature/133 add GitHub actions workflow to build and push docker images to ecr

[AldrionDev]

Implemented and verified GitHub Actions workflow for Docker image build and ECR push.

Added:

• .github/workflows/deploy.yml
• AWS authentication using GitHub repository secrets
• Amazon ECR login
• Backend Docker image build and push
• Frontend Docker image build and push
• latest image tag for the current simple deployment flow

Verified:

• Deploy workflow completed successfully
• Backend image was pushed to ECR with latest tag
• Frontend image was pushed to ECR with latest tag
• ECR image timestamps confirm fresh push from GitHub Actions

Notes:

• Used a dedicated IAM user: github-actions-itassetpulse
• Authentication uses GitHub repository secrets for this demo milestone
• GitHub OIDC is a future improvement
• EKS rollout will be added in Issue Deploy latest images to EKS from GitHub Actions #134