Add comprehensive test suite for current implementation

- Add tests for internal/config package (90.9% coverage)
  - Test all viperConfig getter methods
  - Test LoadConfig with default and environment-specific configs
  - Test error handling for missing config files

- Add tests for internal/di package (88.1% coverage)
  - Test Container lifecycle (NewContainer, Start, Stop)
  - Test providers (ProvideConfig, ProvideLogger, CoreModule)
  - Test lifecycle hooks registration
  - Include mock implementations for testing

- Add tests for internal/logger package (96.5% coverage)
  - Test zapLogger with JSON and console formats
  - Test all logging levels and methods
  - Test middleware (RequestIDMiddleware, LoggingMiddleware)
  - Test context helper functions
  - Include benchmark tests

- Update CI workflow to skip tests when no test files exist
  - Add conditional test execution based on test file presence
  - Add timeout for test execution
  - Verify build when no tests are present

All tests follow Go best practices with table-driven patterns,
parallel execution where safe, and comprehensive coverage.

pkg/logger/global.go

@@ -52,9 +52,9 @@ func ErrorLog(msg string, fields ...Field) {
 // Used as a fallback when no global logger is set.
 type noOpLogger struct{}
 
-func (n *noOpLogger) Debug(msg string, fields ...Field) {}
-func (n *noOpLogger) Info(msg string, fields ...Field)  {}
-func (n *noOpLogger) Warn(msg string, fields ...Field)  {}
-func (n *noOpLogger) Error(msg string, fields ...Field) {}
-func (n *noOpLogger) With(fields ...Field) Logger        { return n }
+func (n *noOpLogger) Debug(msg string, fields ...Field)      {}
+func (n *noOpLogger) Info(msg string, fields ...Field)       {}
+func (n *noOpLogger) Warn(msg string, fields ...Field)       {}
+func (n *noOpLogger) Error(msg string, fields ...Field)      {}
+func (n *noOpLogger) With(fields ...Field) Logger            { return n }
 func (n *noOpLogger) WithContext(ctx context.Context) Logger { return n }