A 58-year-old man presents to his GP with fever, pleuritic chest pain and productive cough with rust-coloured sputum for three days. He has no major comorbidities, a respiratory rate of 22 breaths/min, blood pressure 130/80 mmHg and SpO₂ 95% on room air. Chest X-ray shows a right lower lobe consolidation. He is stable for outpatient management of community-acquired pneumonia. According to Therapeutic Guidelines, what is the most appropriate first-line oral antibiotic regimen?