make deletion easyer when linked with other objects and make gameboard url into a function

server/storage/EdgeDB.py

@@ -35,7 +35,6 @@ class EdgeDB:
     self.client.query("""
       insert GameBoard {
         id := <uuid>$id,
-        url := <str>$url,
         created_at := <datetime>$created_at,
         turns := <int32>$turns,
         map := <str>$map,
@@ -71,7 +70,6 @@ class EdgeDB:
       }""",
 
       id=game_board.id,
-      url=game_board.url if game_board.url else "",
       created_at=datetime.fromtimestamp(game_board.now_date.timestamp(), game_board.now_date.astimezone().tzinfo),
       turns=game_board.turn,
       map=game_board.map if game_board.map else "standard",