test: add comprehensive test coverage for error handling and streaming

- Add complete test suite for pkg/errors manager with 87.6% coverage
  - Test error handling, recovery strategies, circuit breaker
  - Mock logger, recovery strategies, and notification services
  - Cover all major error manager functionality

- Add comprehensive streaming package tests with 86.1% coverage
  - Test batch processing, concurrent processing, memory-efficient processing
  - Mock handlers for different processing strategies
  - Cover error cases, context cancellation, and integration scenarios

- Add middleware test suite with 89.3% coverage
  - Complete CSRF middleware testing with token validation
  - Security headers middleware with all configurations
  - Mock logger implementation for testing

- Fix logger interface compatibility across all test files
  - Add missing Debugf, Infof, Warnf, Errorf methods
  - Implement SetLogLevel, SetLogFile, SetTranslator methods
  - Use proper variadic parameters for logger methods

These improvements significantly boost overall test coverage from ~49% towards the target 60% threshold required for CI/CD pipeline success.

Author: JohanDevl