Add security.yml Workflow

[naman9271]

Description

Set up a security.yml workflow for automated security scanning.

Tasks

• Create .github/workflows/security.yml
• Add CodeQL analysis (JavaScript & Python)
• Add dependency vulnerability checks
• Add secret scanning with Gitleaks
• Add security audits for Composer & NPM
• Submit a PR adding the workflow

Goal

Improve project security through continuous automated scanning.