[TEST-01] Add backend tests to CI pipeline

[grantfox-oss]

Problem

Backend tests exist in micopay/backend/src/tests/ (12 test files) but are not run in CI. The .github/workflows/ci.yml only runs npm run build for the backend — no npm run test step.

This means:

• Code changes can break tests without anyone knowing
• Security tests (security.test.ts, abuse.service.test.ts) never run
• Regression bugs slip through to production

Impact

• Untested code ships to production
• Security vulnerabilities go undetected
• No safety net for refactoring

Proposed Fix

1. Add npm run test step to the backend CI job in .github/workflows/ci.yml
2. Ensure all test files can run without external dependencies (Redis, etc.)
3. If tests require a database, use a service container in CI
4. Add test coverage reporting (optional but recommended)

Files to modify

• .github/workflows/ci.yml (backend job section)

Acceptance Criteria

• Backend tests run on every PR
• CI fails if any test fails
• Tests complete within 5 minutes
• No external service dependencies required for tests

[emmyokolo2525-cyber]

Hi maintainer, I'd like to work on issue. I'll keep the scope aligned with the current architecture and submit a focused, reviewable PR.

[grantfox-oss]

🦊 GrantFox — @emmyokolo2525-cyber has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #339)
2. Your PR will be reviewed by the Micopay maintainers

Good luck! Track your progress on GrantFox.