Brazil’s troubled state-run oil company, Petróleo Brasileiro SA, reported its biggest quarterly loss ever Monday after lower oil prices and higher borrowing costs forced it to write off 49.75 billion reais ($13.79 billion) in assets and investments for last year. Petrobras posted a fourth-quarter loss of BRL36.94 billion, 39% bigger than a year earlier, when its earnings were decimated by write-downs related to a vast…