ALLEN PARK, Mich. — Sam LaPorta didn’t officially practice Thursday, but the Detroit Lions’ ultra-productive rookie tight end took a positive step toward playing in Sunday’s playoff game, going through the team’s morning walkthrough and conducting a workout with the team’s training staff to test his injured knee after the afternoon’s session. “Starting to feel better, day by day, and see where it takes me tomorrow,” LaPorta said. “Really, just taking it a day at a time, because when it first happened, it didn’t feel great, and I feel like I’ve started to bounce back quickly, so we’ll see.” LaP…