Replace hardcoded domains with primary domain setting

app/controllers/webhooks_controller.rb

@@ -30,7 +30,7 @@ class WebhooksController < ApplicationController
   def notify_xmpp(address, amt_sats, memo)
     payload = {
       type: "normal",
-      from: "kosmos.org", # TODO domain config
+      from: Setting.primary_domain,
       to: address,
       subject: "Sats received!",
       body: "#{helpers.number_with_delimiter amt_sats} sats received in your Lightning wallet:\n> #{memo}"