enhance: Packer integration for cloud image builds

[williamzujkowski]

Summary

Add HashiCorp Packer templates to build golden images for cloud platforms.

Requirements

• Packer template for AWS AMI
• Packer template for GCP image
• Packer template for Azure VHD
• Packer template for local QCOW2/OVA
• CI/CD integration for automated image builds

Considerations

• Packer plugin requirements
• Cloud credential handling
• Image versioning strategy
• Build caching for faster iterations

From CLAUDE.md Future Improvements section.