Add server rules (#15769)

app/models/rule.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: rules
+#
+#  id         :bigint(8)        not null, primary key
+#  priority   :integer          default(0), not null
+#  deleted_at :datetime
+#  text       :text             default(""), not null
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#
+class Rule < ApplicationRecord
+  include Discard::Model
+
+  self.discard_column = :deleted_at
+
+  validates :text, presence: true, length: { maximum: 300 }
+
+  scope :ordered, -> { kept.order(priority: :asc) }
+end