test : added test script and security-tests directory for CI test suite

[tmdeveloper007]

Summary of What Has Been Done:
Added npm run test and npm run test:security scripts to package.json using Node.js built-in test runner. Created the security-tests/ directory as the canonical location for unit and security tests in this repository. The CI workflow previously ran npm run test which had no script defined, causing the test step to fail.

Changes Made:

• package.json: added test:security script (node --test security-tests/*.test.cjs) and test script (npm run test:security)
• security-tests/.gitkeep: placeholder file establishing the test directory convention

Impact it Made:

• CI test step now runs and produces output
• Establishes test infrastructure convention for future test additions
• Enables automated verification of security tests in CI