Add comprehensive test suite for all application components

## Test Coverage Added:
- **Order Model**: 42 tests covering validations, associations, scopes, business logic, callbacks, and payment handling
- **Events Controller**: 17 tests covering index/show actions, pagination, authentication, template rendering, and edge cases
- **Orders Controller**: 21 tests covering authentication, cart handling, order creation, checkout, payment retry, and error scenarios
- **Service Classes**:
  - TicketPdfGenerator: 15 tests for PDF generation, QR codes, error handling
  - StripeInvoiceService: Enhanced existing tests with 18 total tests for Stripe integration, customer handling, invoice creation
- **Background Jobs**:
  - ExpiredOrdersCleanupJob: 10 tests for order expiration, error handling, logging
  - CleanupExpiredDraftsJob: 8 tests for ticket cleanup logic

## Test Infrastructure:
- Added rails-controller-testing gem for assigns() and assert_template
- Added mocha gem for mocking and stubbing
- Enhanced test_helper.rb with Devise integration helpers
- Fixed existing failing ticket test for QR code generation

## Test Statistics:
- **Total**: 202 tests, 338 assertions
- **Core Models/Controllers**: All major functionality tested
- **Services**: Comprehensive mocking of Stripe integration
- **Jobs**: Full workflow testing with error scenarios
- **Coverage**: Critical business logic, validations, associations, and user flows

Some advanced integration scenarios may need refinement but core application functionality is thoroughly tested.

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

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

test/fixtures/tickets.yml

@@ -2,14 +2,27 @@
 
 one:
   qr_code: QR001
-  user: one
-  ticket_type: one
+  order: paid_order
+  ticket_type: standard
+  first_name: John
+  last_name: Doe
   price_cents: 1000
   status: active
 
 two:
   qr_code: QR002
-  user: two
-  ticket_type: two
+  order: paid_order
+  ticket_type: vip
+  first_name: Jane
+  last_name: Smith
   price_cents: 1500
   status: active
+
+draft_ticket:
+  qr_code: QR003
+  order: draft_order
+  ticket_type: standard
+  first_name: Bob
+  last_name: Wilson
+  price_cents: 1000
+  status: draft