Package Stigcode for air-gapped deployment

[rdwj]

Stigcode must run in the same air-gapped environments as Sanicode.

Acceptance Criteria:

• Package as a self-contained container image on Red Hat UBI base
• Include all mapping data within the image (no external API calls)
• Provide RPM and pip-installable package for standalone RHEL
• Include in Sanicode's Helm chart as an optional sidecar or separate deployment
• Zero network dependencies at runtime
• Document deployment alongside Sanicode in disconnected OpenShift