feat: Merge PDF ticket generation functionality from feat/pdf-ticket branch

- Add TicketPdfGenerator service for creating PDF tickets with QR codes
- Implement download_ticket action in TicketsController
- Update ticket routes to support both ID and QR code access
- Add to_pdf method to Ticket model using TicketPdfGenerator
- Resolve conflicts between email notifications and PDF ticket features
- Maintain backward compatibility with existing QR code routes

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

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

app/controllers/tickets_controller.rb

@@ -3,7 +3,7 @@
 # This controller now primarily handles legacy redirects and backward compatibility
 # Most ticket creation functionality has been moved to OrdersController
 class TicketsController < ApplicationController
-  before_action :authenticate_user!, only: [ :payment_success, :payment_cancel, :show ]
+  before_action :authenticate_user!, only: [ :payment_success, :payment_cancel, :show, :download_ticket ]
   before_action :set_event, only: [ :checkout, :retry_payment ]
 
 
@@ -48,21 +48,58 @@ class TicketsController < ApplicationController
     end
   end
 
-  # Display informations about the event with QR code
+  # Display ticket details
   def show
-    @ticket = Ticket.joins(order: :user).includes(:event, :ticket_type, order: :user)
-      .find_by(tickets: { qr_code: params[:qr_code] })
+    # Try to find by qr_code first (for backward compatibility)
+    if params[:qr_code].present?
+      @ticket = Ticket.joins(order: :user).includes(:event, :ticket_type, order: :user)
+        .find_by(tickets: { qr_code: params[:qr_code] })
+    else
+      # Find by ticket_id with user ownership check
+      @ticket = Ticket.joins(order: :user).includes(:event, :ticket_type, order: :user).find_by(
+        tickets: { id: params[:ticket_id] },
+        orders: { user_id: current_user.id }
+      )
+    end
 
     if @ticket.nil?
       redirect_to dashboard_path, alert: "Billet non trouvé"
       return
     end
-
     @event = @ticket.event
   rescue ActiveRecord::RecordNotFound
     redirect_to dashboard_path, alert: "Billet non trouvé"
   end
 
+  # Download PDF ticket - only accessible by ticket owner
+  # User must be authenticated to download ticket
+  # TODO: change ID to an unique identifier (UUID)
+  def download_ticket
+    # Find ticket and ensure it belongs to current user
+    @ticket = Ticket.joins(order: :user).includes(:event, :ticket_type, order: :user).find_by(
+      tickets: { id: params[:ticket_id] },
+      orders: { user_id: current_user.id }
+    )
+
+    if @ticket.nil?
+      redirect_to dashboard_path, alert: "Billet non trouvé ou vous n'avez pas l'autorisation d'accéder à ce billet"
+      return
+    end
+
+    # Generate PDF
+    pdf_content = @ticket.to_pdf
+
+    # Send PDF as download
+    send_data pdf_content,
+              filename: "ticket_#{@ticket.id}_#{@ticket.event.name.parameterize}.pdf",
+              type: "application/pdf",
+              disposition: "attachment"
+  rescue ActiveRecord::RecordNotFound
+    redirect_to dashboard_path, alert: "Billet non trouvé"
+  rescue => e
+    Rails.logger.error "Error generating ticket PDF: #{e.message}"
+    redirect_to dashboard_path, alert: "Erreur lors de la génération du billet"
+  end
   private
 
   def set_event