feat: Implement comprehensive enterprise Linux infrastructure portfolio

- Add enterprise-infra-simulator: Ansible-based container infrastructure with provisioning, patching, hardening, and decommissioning playbooks
- Add migration-validation-framework: Python CLI tool for system migration validation with collectors, comparators, and HTML reporting
- Add observability-stack: Complete ELK + Grafana monitoring platform with alerting rules and incident simulation
- Add comprehensive documentation: architecture overview, operational runbooks, and CI/CD pipeline
- Add CHANGELOG.md and AI_CONTEXT.md for project tracking and future development
- Fix Ansible syntax: Update boolean values from 'yes/no' to 'true/false' for modern Ansible compatibility

Demonstrates enterprise Linux infrastructure engineering skills across infrastructure automation, application development, and monitoring.

CHANGELOG.md

@@ -0,0 +1,123 @@
+# Portfolio Changelog
+
+## [1.0.0] - 2026-04-29 - Initial Enterprise Portfolio Release
+
+### Added
+#### Enterprise Infrastructure Simulator
+- **Container-based Linux node simulation** with Docker Compose
+- **Comprehensive Ansible automation suite**:
+  - `provision.yml`: Node provisioning with security hardening, package installation, and service configuration
+  - `patch.yml`: Automated patching with rollback capabilities and notification system
+  - `harden.yml`: Security hardening following CIS benchmarks (firewall, SSH, user management)
+  - `decommission.yml`: Graceful node decommissioning with cleanup and notification
+- **Operational scripts**:
+  - `simulate_scaling.sh`: Infrastructure scaling simulation
+  - `simulate_failure.sh`: Failure injection for testing resilience
+- **Realistic scenarios**:
+  - `scaling_event.yml`: Automated scaling event playbook
+- **Production Makefile** with targets: `up`, `patch`, `harden`, `destroy`
+- **Multi-group Ansible inventory** (`inventory/hosts.ini`) with realistic enterprise structure
+
+#### Migration Validation Framework
+- **Python 3.8+ CLI application** (`cli.py`) with command structure:
+  - `snapshot`: Collect system data from target hosts
+  - `compare`: Compare snapshots for migration validation
+  - `report`: Generate HTML reports from comparison results
+- **Modular collector architecture**:
+  - `collectors/mounts.py`: Filesystem mount point analysis
+  - `collectors/services.py`: System service inventory and status
+  - `collectors/disk_usage.py`: Disk usage statistics and trends
+- **Intelligent comparison engine** (`validators/compare.py`):
+  - Drift detection algorithms
+  - Change categorization (additions, modifications, removals)
+  - Risk assessment scoring
+- **Interactive HTML reporting** (`reports/html_report.py`):
+  - Bootstrap CSS styling
+  - JavaScript-powered filtering and sorting
+  - Detailed change summaries with timestamps
+  - Export capabilities
+
+#### Observability Stack
+- **Complete ELK + Grafana monitoring platform** (`docker-compose.yml`):
+  - Elasticsearch 8.11.0 with security enabled
+  - Logstash 8.11.0 with custom pipelines
+  - Kibana 8.11.0 with pre-configured dashboards
+  - Grafana 10.2.0 with alerting and visualization
+  - Filebeat for log collection
+- **Realistic sample logs** (`logs/sample.log`):
+  - Application logs with various log levels
+  - System logs (nginx, systemd, kernel)
+  - Database logs (PostgreSQL, Redis)
+  - Security events and authentication logs
+- **Enterprise alerting system** (`alerting/alert_rules.yml`):
+  - System resource alerts (CPU, memory, disk)
+  - Service availability monitoring
+  - Application performance alerts
+  - Security incident detection
+  - Multi-channel notifications (email, Slack, PagerDuty)
+- **Incident simulation framework** (`scenarios/incident_simulation.sh`):
+  - CPU spike simulation
+  - Memory leak scenarios
+  - Disk space exhaustion
+  - Network latency/packet loss
+  - Service crash simulation
+  - Database connection issues
+  - Application error bursts
+  - Comprehensive incident scenarios
+
+#### Documentation and Infrastructure
+- **Root documentation**:
+  - `README.md`: Portfolio landing page with project overview and architecture summary
+  - `docs/architecture.md`: Detailed system architecture and design principles
+  - `docs/runbooks.md`: Operational procedures and troubleshooting guides
+- **CI/CD Pipeline** (`.gitea/workflows/ci.yml`):
+  - Ansible syntax validation and linting
+  - Python code testing and type checking
+  - Docker image validation
+  - Security scanning
+  - Documentation generation
+
+### Technical Implementation Details
+- **Languages**: Python 3.8+, YAML, Bash, HTML/CSS/JavaScript
+- **Frameworks**: Ansible, Docker Compose, ELK Stack, Grafana
+- **Infrastructure**: Container-based with production networking
+- **Security**: CIS-compliant hardening, secure defaults, input validation
+- **Monitoring**: Comprehensive alerting with escalation policies
+- **Testing**: Incident simulation, syntax validation, compilation checks
+
+### Quality Assurance
+- ✅ **Syntax validation**: All Ansible playbooks and Python code compile without errors
+- ✅ **Boolean fixes**: Updated Ansible syntax from 'yes/no' to 'true/false' for modern compatibility
+- ✅ **Enterprise naming**: Realistic hostnames, service names, and configurations
+- ✅ **Production quality**: Error handling, logging, health checks, and rollback capabilities
+- ✅ **Documentation**: Comprehensive READMEs, architecture docs, and operational runbooks
+
+### Architecture Highlights
+- **Modular design**: Each project operates independently with clear interfaces
+- **Enterprise patterns**: Multi-tier architecture, service separation, monitoring integration
+- **Scalability**: Container-based deployment with orchestration
+- **Observability**: End-to-end monitoring from infrastructure to application level
+- **Automation**: Infrastructure as Code with comprehensive automation coverage
+
+### Skills Demonstrated
+- **Infrastructure Automation**: Ansible playbook development and enterprise infrastructure management
+- **Application Development**: Python CLI application with modular architecture and reporting
+- **Monitoring & Alerting**: ELK stack configuration, alerting rules, and incident response
+- **Container Orchestration**: Docker Compose for multi-service applications
+- **DevOps Practices**: CI/CD pipeline implementation, documentation, and operational procedures
+- **System Administration**: Linux hardening, patching strategies, and decommissioning procedures
+- **Security**: CIS benchmarks implementation and security monitoring
+- **Data Analysis**: System data collection, comparison algorithms, and visualization
+
+### Future Expansion Points
+- Kubernetes orchestration integration
+- Multi-cloud deployment support
+- Advanced monitoring dashboards
+- Machine learning-based anomaly detection
+- Integration with enterprise tools (Jira, ServiceNow)
+- Performance optimization and benchmarking
+- Compliance automation (PCI-DSS, HIPAA)
+- Disaster recovery procedures
+
+---
+*Portfolio created to demonstrate enterprise-level Linux infrastructure engineering capabilities across the full technology stack.*