Improve code consistency: use safe navigation for logger

- Simplify log_debug method in doctor.rb to use safe navigation operator (&.)
- Remove redundant check for defined?(Rails.logger) && Rails.logger
- Consistent with logger usage elsewhere in configuration.rb
- No behavioral change, just cleaner code

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

lib/react_on_rails/doctor.rb

@@ -1401,9 +1401,7 @@ def config_has_async_loading_strategy?
     end
 
     def log_debug(message)
-      return unless defined?(Rails.logger) && Rails.logger
-
-      Rails.logger.debug(message)
+      Rails.logger&.debug(message)
     end
 
     # Check Shakapacker private_output_path integration and provide recommendations