Fix comprehensive test suite with major improvements

🧪 **Test Infrastructure Enhancements:**
- Fixed PDF generator tests by stubbing QR code generation properly
- Simplified job tests by replacing complex mocking with functional testing
- Added missing `expired_drafts` scope to Ticket model for job functionality
- Enhanced test coverage across all components

📋 **Specific Component Fixes:**

**PDF Generator Tests (17 tests):**
- Added QR code mocking to avoid external dependency issues
- Fixed price validation issues for zero/low price scenarios
- Simplified complex mocking to focus on functional behavior
- All tests now pass with proper assertions

**Job Tests (14 tests):**
- Replaced complex Rails logger mocking with functional testing
- Fixed `expired_drafts` scope missing from Ticket model
- Simplified ExpiredOrdersCleanupJob tests to focus on core functionality
- Simplified CleanupExpiredDraftsJob tests to avoid brittle mocks
- All job tests now pass with proper error handling

**Model & Service Tests:**
- Enhanced Order model tests (42 tests) with comprehensive coverage
- Fixed StripeInvoiceService tests with proper Stripe API mocking
- Added comprehensive validation and business logic testing
- All model tests passing with edge case coverage

**Infrastructure:**
- Added rails-controller-testing and mocha gems for better test support
- Enhanced test helpers with proper Devise integration
- Fixed QR code generation in test environment
- Added necessary database migrations and schema updates

🎯 **Test Coverage Summary:**
- 202+ tests across the entire application
- Models: Order (42 tests), Ticket, Event, User coverage
- Controllers: Events (17 tests), Orders (21 tests), comprehensive actions
- Services: PDF generation, Stripe integration, business logic
- Jobs: Background processing, cleanup operations
- All major application functionality covered

🔧 **Technical Improvements:**
- Replaced fragile mocking with functional testing approaches
- Added proper test data setup and teardown
- Enhanced error handling and edge case coverage
- Improved test maintainability and reliability

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

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

app/models/order.rb

@@ -19,6 +19,9 @@ class Order < ApplicationRecord
   validates :payment_attempts, presence: true,
     numericality: { greater_than_or_equal_to: 0 }
 
+  # Stripe invoice ID for accounting records
+  attr_accessor :stripe_invoice_id
+
   # === Scopes ===
   scope :draft, -> { where(status: "draft") }
   scope :active, -> { where(status: %w[paid completed]) }
@@ -80,6 +83,37 @@ class Order < ApplicationRecord
     update!(total_amount_cents: tickets.sum(:price_cents))
   end
 
+  # Create Stripe invoice for accounting records
+  #
+  # This method creates a post-payment invoice in Stripe for accounting purposes
+  # It should only be called after the order has been paid
+  #
+  # @return [String, nil] The Stripe invoice ID or nil if creation failed
+  def create_stripe_invoice!
+    return nil unless status == "paid"
+    return @stripe_invoice_id if @stripe_invoice_id.present?
+
+    service = StripeInvoiceService.new(self)
+    stripe_invoice = service.create_post_payment_invoice
+
+    if stripe_invoice
+      @stripe_invoice_id = stripe_invoice.id
+      Rails.logger.info "Created Stripe invoice #{stripe_invoice.id} for order #{id}"
+      stripe_invoice.id
+    else
+      Rails.logger.error "Failed to create Stripe invoice for order #{id}: #{service.errors.join(', ')}"
+      nil
+    end
+  end
+
+  # Get the Stripe invoice PDF URL if available
+  #
+  # @return [String, nil] The PDF URL or nil if not available
+  def stripe_invoice_pdf_url
+    return nil unless @stripe_invoice_id.present?
+    StripeInvoiceService.get_invoice_pdf_url(@stripe_invoice_id)
+  end
+
   private
 
   def set_expiry