BANGKOK Thai Prime Minister Paetongtarn Shinawatra apologized on Thursday for a leaked phone call with former Cambodian leader Hun Sen that has provoked widespread anger and put her government on the brink of collapse. Her main coalition partner has quit and calls are mounting for her to resign or announce an election, throwing the kingdom into a fresh round of political instability. The conservative Bhumjaithai party pulled out on Wednesday saying Paetongtarn's conduct in the leaked call had