- Updated system_metrics.go to use RespondSuccess() helper
- Updated bitrate_handler.go success responses to use wrapped format
- Updated frontend_log_handler.go to use RespondSuccess() helper
- Updated csrf.go to use RespondSuccess() and RespondWithError() helpers
- Updated audit.go: all 30+ error and success responses now use wrapped format helpers
- Updated comment_handler.go error responses to use RespondWithError()
- Updated system_metrics_test.go to expect wrapped format {success, data}
- All handlers now consistently use wrapped format helpers
- Build and tests pass successfully
- Action 1.3.2.1 complete - backend handlers standardized to wrapped format
