Add Open Redirect Fix and DevSecOps Security Scanning

[IT24102493]

Description

This pull request implements the Member 4 security improvements for the NodeGoat DevSecOps project.

Changes Made

• Fixed the Open Redirect vulnerability in the /learn route.
• Added Semgrep SAST scanning to identify source-code security issues.
• Added Gitleaks secret scanning to detect exposed secrets and private keys.
• Added Trivy container vulnerability scanning with HIGH/CRITICAL severity enforcement.
• Added dependency security auditing using npm audit.
• Added .env.example for safe environment variable configuration.
• Updated .gitignore and .dockerignore to prevent sensitive files from being included.
• Removed the exposed private key from the Docker build context.
• Updated the Dockerfile with ca-certificates to support secure package installation.
• Integrated the security checks into the GitHub Actions DevSecOps pipeline.

Testing

• Verified the Open Redirect exploit before the fix.
• Verified the malicious redirect was blocked after the fix.
• Ran Semgrep before and after the fix.
• Ran Gitleaks secret scanning.
• Ran Trivy against the Docker image.
• Verified that the Trivy HIGH/CRITICAL security gate can detect vulnerabilities.

Branch

member4/security-scanning