A 40-year-old man presents with a 3-day history of fever, productive cough with green sputum and pleuritic chest pain. He is a non-smoker, previously well. On examination, temperature is 38.4 °C, respiratory rate 22/min, BP 122/74 mmHg and SpO₂ 95% on room air. Chest auscultation reveals right lower lobe crackles. CURB-65 score is 0. According to Australian CAP guidance, what is the most appropriate empirical oral antibiotic in the community?