Aggiunge il rilevamento di invio e apertura delle email di campagna.

Ogni destinatario mostra se la mail è partita e se è stata aperta, con conteggi in dashboard.

Co-authored-by: Cursor <cursoragent@cursor.com>

test/controllers/mailings_controller_test.rb

@@ -65,6 +65,8 @@ class MailingsControllerTest < ActionDispatch::IntegrationTest
     assert_equal "contacted", opportunities(:deal).pipeline_stage
     assert_equal 2, ActionMailer::Base.deliveries.size
     assert_equal "Ciao ASD Test Calcio", ActionMailer::Base.deliveries.last.subject
+    body = (ActionMailer::Base.deliveries.last.html_part || ActionMailer::Base.deliveries.last).body.to_s
+    assert_match(%r{/t/o/#{Regexp.escape(recipient.reload.tracking_token)}\.gif}, body)
   end
 
   test "queue send requires test email first" do
@@ -96,7 +98,9 @@ class MailingsControllerTest < ActionDispatch::IntegrationTest
     mail = ActionMailer::Base.deliveries.last
     assert_equal [users(:admin).email], mail.to
     assert_match(/\[TEST\]/, mail.subject)
+    body = (mail.html_part || mail).body.to_s
     assert_match(/Società Prova/, mail.subject)
+    assert_no_match(%r{/t/o/}, body)
     assert mailing.reload.tested?
     assert_equal users(:admin).email, mailing.test_sent_to
   end