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/jobs/event_reminder_job_test.rb

@@ -23,9 +23,9 @@ class EventReminderJobTest < ActiveJob::TestCase
   test "logs error when mailer fails" do
     # Mock a failing mailer
     TicketMailer.stubs(:event_reminder).raises(StandardError.new("Test error"))
-    
+
     Rails.logger.expects(:error).with(regexp_matches(/Failed to send event reminder/))
-    
+
     EventReminderJob.perform_now(@event.id, 7)
   end
-end
+end