Check into the Mandarin Oriental on the middle of the Las Vegas Strip, look out the window of your room and you might see something you didn’t quite expect. Yes, there are people living in the building across from you. The lights and TVs and stoves are on at the Veer Towers, where condos have been unloaded briskly after Pordes Residential Sales & Marketing, a Miami-based firm known for rescuing troubled projects, relaunched sales this year.