A 60-year-old man with a history of smoking presents with progressive exertional dyspnoea and a chronic cough productive of sputum. Spirometry shows FEV₁/FVC ratio 0.55 and FEV₁ 55% predicted, with minimal reversibility after bronchodilator. He has had two moderate exacerbations in the last year treated with oral prednisolone and antibiotics. According to COPD-X and related Australian guidance, which maintenance regimen is most appropriate?