feat(sec-pipeline): implement unified container scanning architecture and SAST integration

[moghit-eou]

• Consolidate SAST (Hadolint/OpenGrep) and SCA (Trivy/OSV) into a single Python orchestrator.
• Implement unified SARIF merging for centralized GitHub Security tab reporting.
• Refactor setup-tools.sh to use modular CLI flags (--install-tool, --sbom-ecosystem) for dynamic binary installation.
• Standardize pipeline failure gates across both qualitative severity and CVSS scores.

Follows OWASP DevSecOps guidelines for Dockerfile/container hardening.

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