Tests: Add Unit tests

#### **Description:**

This issue proposes adding unit and integration tests to improve the reliability and maintainability of the `gobglbridge` codebase. Currently, there is a lack of comprehensive automated testing, which is essential to ensure new changes do not break existing functionality.

#### **Objectives:**

- **Unit Tests:** Cover core functions, handle typical inputs, edge cases, and errors, using mocks where necessary.
- **Integration Tests:** Test real-world scenarios, including interactions between modules and external services, focusing on transaction processing and error handling.
- **Test Coverage:** Aim for at least 80% coverage using tools like `go test -cover`, with integration into CI/CD pipelines.

#### **Benefits:**

- **Improved Code Quality:** Catch bugs and regressions early.
- **Faster Development:** Allow safe and confident code changes.
- **Documentation:** Tests serve as documentation for expected behavior.
- **Scalability:** Ensure future changes don’t break existing functionality.

#### **Deliverables:**

- Unit and integration tests in a `tests/` directory.
- Documentation on running tests.
- CI/CD updates to automate test execution.
- Initial test coverage of at least 50%, with plans to increase.

#### **Request for Feedback:**

- Suggestions for test cases, scenarios, and preferred testing tools (e.g., `testify`, `Ginkgo`) are welcome.

Start by reviewing the existing gobglbridge packages and the proposed tests/ directory, then run go test -cover to establish the current baseline. Identify core functions, transaction processing, error handling, and external-service interactions that need coverage. Done means unit and integration tests exist, test-running documentation is added, CI/CD runs them, and the stated coverage target is measured.

Written by the indexing model from the issue text.