A 24-year-old woman presents with recurrent episodes of wheeze and chest tightness triggered by exercise and viral infections. She uses a salbutamol inhaler several times per week with good short-term relief. Spirometry confirms reversible airflow obstruction consistent with asthma. According to the 2021 Canadian Thoracic Society asthma guideline, which of the following is the most appropriate controller strategy for long-term management?