Onion Extract in Human Health: Clinical Evidence and Mechanistic Insights across Cardio-metabolic, Infectious, Hepatic, Neuro-inflammatory, and Barrier Disorders An Integrative Review of Human Clinical Studies and Mechanistic Pathways Supporting Onion Extract as a Multi-System Nutraceutical 0009-0007-5798-1996 DOI: 10.5281/zenodo.17528695