Add DevSecOps security scanning and container security gate

[IT24102493]

Member 4 – DevSecOps Security Scanning

Changes

• Added Semgrep SAST scanning to the DevSecOps pipeline.
• Added Gitleaks secret scanning.
• Added Trivy container vulnerability scanning.
• Added a Trivy HIGH/CRITICAL security gate.
• Added .env.example for safe environment-variable documentation.
• Removed the private key from the Docker build context.
• Added Docker ignore rules for sensitive files.
• Fixed the Open Redirect vulnerability in /learn.

Security Validation

• Semgrep: Passed
• Gitleaks: Passed
• Trivy: Detects HIGH/CRITICAL vulnerabilities and fails the security gate as configured.
• Dependency audit: Detects existing HIGH/CRITICAL dependency vulnerabilities.

Branch

member4/security-scanning