Add documentation for existing Zero Logger integration and feature-level logging tests

[anzal1]

We are already using Zero Logger for structured logging. This issue tracks the following:

1. Documentation:

• Explain how Zero Logger is integrated in the codebase
• Describe log format, levels, and structure
• Document how to view logs in different environments (e.g., dev, staging, prod)
• Include guidelines on logging best practices and adding new logs

2. Feature-level tests:

• Add tests to verify that key flows produce expected logs
• Use mocks/interceptors to validate log output where feasible

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Acceptance Criteria

• Documentation for Zero Logger is added to the README or appropriate location
• At least one feature-level test asserts expected log output for a core functionality
• All tests pass in CI

[P09s]

Hi, I’d like to work on this issue. I’ll add logging documentation and include a feature-level test to validate log output for a core flow.