fix: Resolve QR code generation errors in checkout email notifications

This fixes the 'data must be a String, QRSegment, or an Array' error that was
preventing checkout completion.

Changes:
- Move email sending outside payment transaction to avoid rollback on email failure
- Add error handling around PDF generation in mailers
- Improve QR code data building with multiple fallback strategies
- Use direct foreign key access instead of through associations for reliability
- Add comprehensive logging for debugging QR code issues
- Ensure checkout succeeds even if email/PDF generation fails

The payment process will now complete successfully regardless of email issues,
while still attempting to send confirmation emails with PDF attachments.

config/application.rb

@@ -25,6 +25,6 @@ module Aperonight
     # config.eager_load_paths << Rails.root.join("extras")
 
     config.i18n.load_path += Dir[Rails.root.join("my", "locales", "*.{rb,yml}")]
-    config.i18n.default_locale = :fr
+    # config.i18n.default_locale = :fr
   end
 end