A 38-year-old man from Delhi presents with a 2-year history of progressive nasal obstruction, rhinorrhoea, and post-nasal drip. He reports recurrent sinusitis requiring multiple courses of antibiotics. On nasal endoscopy, bilateral smooth, pale, glistening masses are seen arising from the lateral nasal wall near the ostiomeatal complex. CT paranasal sinuses shows opacification of the maxillary and ethmoid sinuses with polypoid masses. He denies asthma, but spirometry reveals mild airflow obstruction. What is the most likely diagnosis?