feat: handle unsubscribe

src/domain/__init__.py

@@ -11,6 +11,7 @@ __all__ = (
     'TargetChannelStatus',
     'CreativeStatus',
     'PlacementStatus',
+    'SubscriptionStatus',
     'InviteLinkType',
     'PostViewsAvailability',
     'LoginToken',
@@ -49,6 +50,6 @@ from .login_token import LoginToken
 from .placement import InviteLinkType, Placement, PlacementStatus, PostViewsAvailability
 from .placement_views_history import PlacementViewsHistory
 from .subscriber import Subscriber
-from .subscription import Subscription
+from .subscription import Subscription, SubscriptionStatus
 from .target_channel import TargetChannel, TargetChannelStatus
 from .user import User