Persist UI settings, add missing localizations for German

app/controllers/api/web/settings_controller.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class Api::Web::SettingsController < ApiController
+  respond_to :json
+
+  before_action :require_user!
+
+  def update
+    setting      = Web::Setting.where(user: current_user).first_or_initialize(user: current_user)
+    setting.data = params[:data]
+    setting.save!
+
+    render_empty
+  end
+end