Add Secure-AI-Flow security-first methodology scaffold

[solomonsjoseph]

Summary

• Initialize the repository with the Secure-AI-Flow security-first methodology scaffold from the provided ZIP package.
• Preserve the package directory structure and content.
• Mark validation scripts executable.

Validation

• scripts/check-security-methodology.sh passed.
• scripts/verify-methodology.sh passed.

ZIP content changes

• No content changes from the ZIP package.
• scripts/check-security-methodology.sh and scripts/verify-methodology.sh have executable mode set as requested.

Note

• The repository had no existing main ref, so an empty main branch was created first to provide the requested PR base.