feat: Portal endpoint (#4633)

app/models/folder.rb

@@ -0,0 +1,20 @@
+# == Schema Information
+#
+# Table name: folders
+#
+#  id          :bigint           not null, primary key
+#  name        :string
+#  created_at  :datetime         not null
+#  updated_at  :datetime         not null
+#  account_id  :integer          not null
+#  category_id :integer          not null
+#
+class Folder < ApplicationRecord
+  belongs_to :account
+  belongs_to :category
+  has_many :articles, dependent: :nullify
+
+  validates :account_id, presence: true
+  validates :category_id, presence: true
+  validates :name, presence: true
+end