fix(leaderboard): filter out 0xp users

backend/routers/leaderboards.py

@@ -118,6 +118,7 @@ def get_active_users(limit: int = 10, session: Session = Depends(get_session)):
         )
         .join(User, User.id == Profile.user_id)
         .join(Review, Review.user_id == User.id)
+        .where(User.xp > 0)
         .group_by(Profile.id)
         .order_by(desc("review_count"))
         .limit(limit)