Remove orphaned notifications, add scopes param to app create API

app/models/follow.rb

@@ -7,6 +7,8 @@ class Follow < ApplicationRecord
   belongs_to :account
   belongs_to :target_account, class_name: 'Account'
 
+  has_one :notification, as: :activity, dependent: :destroy
+
   validates :account, :target_account, presence: true
   validates :account_id, uniqueness: { scope: :target_account_id }