A 32-year-old woman presents to the emergency department with pleuritic chest pain and dyspnoea 2 days after a long-haul flight from Europe. She has a swollen, tender left calf. Vital signs: BP 118/70 mmHg, HR 108 bpm, RR 22/min, SpO₂ 93% on room air, afebrile. CT pulmonary angiography confirms a segmental pulmonary embolism. There is no haemodynamic compromise. According to Australasian VTE guidelines, which is the most appropriate initial outpatient anticoagulation strategy?