Upgrade CI/CD automation, pre-commit hooks, and testing

[zulfikar-ditya]

Bring up the automation, test coverage, and developer experience:

Checklist:

• Add and enforce Husky pre-commit hooks for lint/type/style check
• Update CI (GitHub Actions) for lint, type, unit, and integration test runs
• Enforce code coverage minimums
• Add integration and e2e tests with Fastify's inject and/or supertest
• Document how to run/test/debug locally

Rationale:
Makes the repo production-ready for teams and contributions. Testing is a critical part of sustainable, high-quality releases.

[zulfikar-ditya]

partial complete, but we need test now