DALLAS — As Dallas rookie Cooper Flagg set the NBA record for points by a teenager with 49 on Thursday night in a 123-121 loss to Charlotte, he broke the franchise rookie scoring record he shared with Mark Aguirre — whose jersey was retired at halftime.“Mark Aguirre is special. Such a special night for him and the whole organization,” said Flagg, who turned 19 in December. “I just feel blessed. It’s a pretty cool thing.”“You saw history,” Mavericks coach Jason Kidd said. “We saw history at halftime, and we got to see a young man play the game at a very high level. To have Mark in the building and break his record was pretty special.”Also special for the No. 1 draft pick last summer from Duke was playing his first NBA game against Kon Knueppel, his roommate as Blue Devils freshmen last season. Knueppel, drafted fourth, set his own career record with 34 points and hit the two winning free throws with 4.1 seconds left after being fouled at the rim by Flagg.“Cooper, he played like the best player we’ve played all season,” said Knueppel, who set a franchise rookie record hitting eight 3-pointers. “He had a heck of a game, he’s a heck of a player, and he’s going to have a heck of a career.”Flagg referred to Knueppel as his “brother for life.”Cliff Robinson set the previous NBA teen record of 45 at age 19 for New Jersey in a …