The Boston Celtics have officially signed former San Antonio Spurs first-round pick Luka Samanic. View the original article to see embedded media. The Boston Celtics are coming off an incredible season where they made it all the way to the NBA Finals (they lost to the Golden State Warriors in six games). They have now been to the Eastern Conference Finals in three out of the last five seasons, so clearly, they are one of the premier teams in the entire NBA. The Celtics will play their first game of the regular season on October 18 when they host James…