Add notifications of severed relationships (#27511)

app/models/severed_relationship.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: severed_relationships
+#
+#  id                              :bigint(8)        not null, primary key
+#  relationship_severance_event_id :bigint(8)        not null
+#  local_account_id                :bigint(8)        not null
+#  remote_account_id               :bigint(8)        not null
+#  direction                       :integer          not null
+#  show_reblogs                    :boolean
+#  notify                          :boolean
+#  languages                       :string           is an Array
+#  created_at                      :datetime         not null
+#  updated_at                      :datetime         not null
+#
+class SeveredRelationship < ApplicationRecord
+  belongs_to :relationship_severance_event
+  belongs_to :local_account, class_name: 'Account'
+  belongs_to :remote_account, class_name: 'Account'
+
+  enum direction: {
+    passive: 0, # analogous to `local_account.passive_relationships`
+    active: 1, # analogous to `local_account.active_relationships`
+  }
+
+  scope :about_local_account, ->(account) { where(local_account: account) }
+
+  scope :active, -> { where(direction: :active) }
+  scope :passive, -> { where(direction: :passive) }
+
+  def account
+    active? ? local_account : remote_account
+  end
+
+  def target_account
+    active? ? remote_account : local_account
+  end
+end