feat: add comprehensive GitHub Actions CI/CD workflows

- Add CI workflow for Docker builds, shell linting, and security scanning
- Add Docker workflow for multi-service container builds and validation
- Add Security workflow for vulnerability scanning and secret detection
- Add Maintenance workflow for cleanup and health monitoring
- Add Release workflow for version management and changelog generation
- Add Deploy workflow for production deployments
- Add Cleanup workflow for registry maintenance

All workflows adapted from Tux project structure for IRC.atl.chat infrastructure

Author: kzndotsh