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>

app/jobs/event_reminder_job.rb

@@ -3,7 +3,7 @@ class EventReminderJob < ApplicationJob
 
   def perform(event_id, days_before)
     event = Event.find(event_id)
-    
+
     # Find all users with active tickets for this event
     users_with_tickets = User.joins(orders: { tickets: :ticket_type })
                             .where(ticket_types: { event: event })
@@ -16,4 +16,4 @@ class EventReminderJob < ApplicationJob
       Rails.logger.error "Failed to send event reminder to user #{user.id} for event #{event.id}: #{e.message}"
     end
   end
-end
+end