fix Add Quality Assurance & Security Audit Report for Nightly Workflow Implementation

- Created a comprehensive QA report detailing the audit of three GitHub Actions workflows: propagate-changes.yml, nightly-build.yml, and supply-chain-verify.yml.
- Included sections on pre-commit hooks, YAML syntax validation, security audit findings, logic review, best practices compliance, and specific workflow analysis.
- Highlighted strengths, minor improvements, and recommendations for enhancing security and operational efficiency.
- Documented compliance with SLSA Level 2 and OWASP security best practices.
- Generated report date: 2026-01-13, with a next review scheduled after Phase 3 implementation or 90 days from deployment.

.gitignore

@@ -231,9 +231,11 @@ test-results/local.har
 /trivy-*.txt
 
 # -----------------------------------------------------------------------------
-# SBOM artifacts
+# SBOM and vulnerability scan artifacts
 # -----------------------------------------------------------------------------
 sbom*.json
+grype-results*.json
+grype-results*.sarif
 
 # -----------------------------------------------------------------------------
 # Docker Overrides (new location)