Two months after Taylor Swift and Travis Kelce said “I do” at Madison Square Garden in front of 1,000 of their closest friends, somehow not one picture has leaked. While that’s testament to the couple’s ultra-tight security, one eyewitness has spilled previously unrevealed details from the celebrity wedding of the year (perhaps decade) to Page Six. Our source told us, for the ceremony Swift made her way down the aisle from the arena’s sixth floor — in an area normally home to a concession stand — before changing into a shorter party dress for the reception. The later festivities took place on the opposite side of the venue, where a…