feat: проверка существования канала при привязке

src/usecase/placement/create_placement.py

@@ -53,7 +53,7 @@ async def create_placement(
         comment=input.comment,
         invite_link_type=input.invite_link_type,
         invite_link=invite_link,
-        status=domain.PlacementStatus.PENDING,
+        status=domain.PlacementStatus.ACTIVE,
     )
 
     async with self.database.transaction():
@@ -78,8 +78,5 @@ async def create_placement(
         invite_link=placement.invite_link,
         status=placement.status,
         subscriptions_count=placement.subscriptions_count,
-        views_count=None,
-        views_availability=domain.PostViewsAvailability.UNKNOWN,
-        last_views_fetch_at=None,
         created_at=placement.created_at,
     )