feat: Complete email notifications system with comprehensive functionality

- Implement comprehensive email notification system for ticket purchases and event reminders
- Add event reminder job with configurable scheduling
- Enhance ticket mailer with QR code generation and proper formatting
- Update order model with email delivery tracking
- Add comprehensive test coverage for all email functionality
- Configure proper mailer settings and disable annotations
- Update backlog to reflect completed email features

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

test/integration/email_notifications_integration_test.rb

@@ -56,7 +56,7 @@ class EmailNotificationsIntegrationTest < ActionDispatch::IntegrationTest
   test "sends purchase confirmation email when order is marked as paid" do
     # Mock PDF generation to avoid QR code issues
     @ticket.stubs(:to_pdf).returns("fake_pdf_content")
-    
+
     assert_emails 1 do
       @order.mark_as_paid!
     end
@@ -78,12 +78,12 @@ class EmailNotificationsIntegrationTest < ActionDispatch::IntegrationTest
     end
 
     email = ActionMailer::Base.deliveries.last
-    assert_equal [@user.email], email.to
+    assert_equal [ @user.email ], email.to
     assert_equal "Rappel : #{@event.name} dans une semaine", email.subject
   end
 
   test "event reminder job schedules emails for users with tickets" do
-    # Setup: mark order as paid and activate tickets  
+    # Setup: mark order as paid and activate tickets
     @ticket.stubs(:to_pdf).returns("fake_pdf_content")
     @order.mark_as_paid!
 
@@ -95,7 +95,7 @@ class EmailNotificationsIntegrationTest < ActionDispatch::IntegrationTest
 
     assert_equal 1, ActionMailer::Base.deliveries.size
     email = ActionMailer::Base.deliveries.last
-    assert_equal [@user.email], email.to
+    assert_equal [ @user.email ], email.to
     assert_match "une semaine", email.subject
   end
-end
+end