Add db table and models

app/models/push/subscription.rb

@@ -0,0 +1,7 @@
+class Push::Subscription < ApplicationRecord
+  belongs_to :user
+
+  def notification(**params)
+    WebPush::Notification.new(**params, badge: user.notifications.unread.count, endpoint: endpoint, p256dh_key: p256dh_key, auth_key: auth_key)
+  end
+end