add default user signatures

lib/user_configs.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+module UserConfigs
+  module_function
+
+  def load_signature(user)
+    return if user.blank?
+
+    uuid = user.user_configs.find_or_initialize_by(key: UserConfig::SIGNATURE_KEY).value
+
+    ActiveStorage::Attachment.find_by(uuid:, record: user, name: 'signature') if uuid.present?
+  end
+end