Add GitHub Actions workflow for dependency and security checks

[rahul810050]

The project currently does not have automated checks for dependency vulnerabilities
or security issues.

This issue proposes adding a GitHub Actions workflow focused on dependency and
security validation.

The security workflow should:

• Trigger on pull requests and scheduled runs.
• Install project dependencies.
• Run dependency security checks (e.g. npm audit).
• Optionally integrate with tools like Dependabot or existing SonarCloud setup.
• Report vulnerabilities and fail on high or critical issues (configurable).

Benefits:

• Early detection of vulnerable dependencies.
• Improved security posture of the application.
• Reduced risk of shipping known vulnerabilities.
• Aligns the project with modern security best practices.

This workflow complements existing CI checks by focusing on dependency health
and security.