feat: Implement complete event ticketing system with Stripe integration and email confirmations

- Enhanced events index page with improved visual design and better information display
- Completely redesigned event show page with modern layout, ticket selection, and checkout functionality
- Implemented Stripe payment processing for ticket purchases
- Created ticket generation system with PDF tickets and QR codes
- Added email confirmation system with ticket attachments
- Updated database configuration to use SQLite for easier development setup
- Fixed gem dependencies and resolved conflicts
- Improved error handling throughout the checkout process
- Enhanced Stimulus controller for ticket cart management
- Added proper redirect handling for successful and cancelled payments

app/models/ticket.rb

@@ -12,6 +12,17 @@ class Ticket < ApplicationRecord
   validates :status, presence: true, inclusion: { in: %w[active used expired refunded] }
 
   before_validation :set_price_from_ticket_type, on: :create
+  before_validation :generate_qr_code, on: :create
+
+  # Generate PDF ticket
+  def to_pdf
+    TicketPdfGenerator.new(self).generate
+  end
+
+  # Price in euros (formatted)
+  def price_euros
+    price_cents / 100.0
+  end
 
   private
 
@@ -19,4 +30,13 @@ class Ticket < ApplicationRecord
     return unless ticket_type
     self.price_cents = ticket_type.price_cents
   end
+
+  def generate_qr_code
+    return if qr_code.present?
+    
+    loop do
+      self.qr_code = SecureRandom.uuid
+      break unless Ticket.exists?(qr_code: qr_code)
+    end
+  end
 end