add the claim mechanism

app/models/claim.rb

@@ -0,0 +1,21 @@
+# == Schema Information
+#
+# Table name: claims
+#
+#  id         :integer          not null, primary key
+#  issue_id   :integer
+#  user_id    :integer
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#  note       :text(65535)
+#
+# Indexes
+#
+#  index_claims_on_issue_id  (issue_id)
+#  index_claims_on_user_id   (user_id)
+#
+
+class Claim < ApplicationRecord
+    belongs_to :user, foreign_key: :user_id
+    scope :claim_includes, ->{includes(:user)}
+end