fix: Replace Prawn with Grover for PDF ticket generation

- Replace Prawn PDF generation with Grover (Chrome headless) for better compatibility
- Add HTML-based ticket template with embedded CSS styling
- Implement robust Grover loading with fallback to HTML download
- Add QR code generation methods to Ticket model
- Remove legacy TicketPdfGenerator service and tests
- Update PDF generation in TicketsController with proper error handling

The new implementation provides:
- Better HTML/CSS rendering for ticket layouts
- More reliable PDF generation using Chrome engine
- Fallback mechanism for better user experience
- Cleaner separation of template rendering and PDF conversion

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

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

app/services/ticket_pdf_generator.rb

@@ -1,118 +0,0 @@
-require "prawn"
-require "prawn/qrcode"
-require "rqrcode"
-
-# PDF ticket generator service using Prawn
-#
-# Generates PDF tickets with QR codes for event entry validation
-# Includes event details, venue information, and unique QR code for each ticket
-class TicketPdfGenerator
-  # Suppress Prawn's internationalization warning for built-in fonts
-  Prawn::Fonts::AFM.hide_m17n_warning = true
-  attr_reader :ticket
-
-  def initialize(ticket)
-    @ticket = ticket
-  end
-
-  def generate
-    Prawn::Document.new(page_size: [ 350, 600 ], margin: 20) do |pdf|
-      # Header
-      pdf.fill_color "2D1B69"
-      pdf.font "Helvetica", style: :bold, size: 24
-      pdf.text "ApéroNight", align: :center
-      pdf.move_down 10
-
-      # Event name
-      pdf.fill_color "000000"
-      pdf.font "Helvetica", style: :bold, size: 18
-      pdf.text ticket.event.name, align: :center
-      pdf.move_down 20
-
-      # Ticket info box
-      pdf.stroke_color "E5E7EB"
-      pdf.fill_color "F9FAFB"
-      pdf.rounded_rectangle [ 0, pdf.cursor ], 310, 150, 10
-      pdf.fill_and_stroke
-
-      pdf.move_down 10
-      pdf.fill_color "000000"
-      pdf.font "Helvetica", size: 12
-
-      # Customer name
-      pdf.text "Ticket Holder:", style: :bold
-      pdf.text "#{ticket.first_name} #{ticket.last_name}"
-      pdf.move_down 8
-
-      # Ticket details
-      pdf.text "Ticket Type:", style: :bold
-      pdf.text ticket.ticket_type.name
-      pdf.move_down 8
-
-      pdf.text "Price:", style: :bold
-      pdf.text "€#{ticket.price_euros}"
-      pdf.move_down 8
-
-      pdf.text "Date & Time:", style: :bold
-      pdf.text ticket.event.start_time.strftime("%B %d, %Y at %I:%M %p")
-      pdf.move_down 20
-
-      # Venue information
-      pdf.fill_color "374151"
-      pdf.font "Helvetica", style: :bold, size: 14
-      pdf.text "Venue Information"
-      pdf.move_down 8
-
-      pdf.font "Helvetica", size: 11
-      pdf.text ticket.event.venue_name, style: :bold
-      pdf.text ticket.event.venue_address
-      pdf.move_down 20
-
-      # QR Code
-      pdf.fill_color "000000"
-      pdf.font "Helvetica", style: :bold, size: 14
-      pdf.text "Ticket QR Code", align: :center
-      pdf.move_down 10
-
-      # Ensure all required data is present before generating QR code
-      if ticket.qr_code.blank?
-        raise "Ticket QR code is missing"
-      end
-
-      qr_code_data = {
-        ticket_id: ticket.id,
-        qr_code: ticket.qr_code,
-        event_id: ticket.event&.id,
-        user_id: ticket.user&.id
-      }.compact.to_json
-
-      # Validate QR code data before creating QR code
-      if qr_code_data.blank? || qr_code_data == "{}"
-        raise "QR code data is empty or invalid"
-      end
-
-      # Generate QR code - prawn-qrcode expects the data string directly
-      pdf.print_qr_code(qr_code_data, extent: 120, align: :center)
-
-      pdf.move_down 15
-
-      # QR code text
-      pdf.font "Helvetica", size: 8
-      pdf.fill_color "6B7280"
-      pdf.text "QR Code: #{ticket.qr_code[0..7]}...", align: :center
-
-      # Footer
-      pdf.move_down 30
-      pdf.stroke_color "E5E7EB"
-      pdf.horizontal_line 0, 310
-      pdf.move_down 10
-
-      pdf.font "Helvetica", size: 8
-      pdf.fill_color "6B7280"
-      pdf.text "This ticket is valid for one entry only.", align: :center
-      pdf.text "Present this ticket at the venue entrance.", align: :center
-      pdf.move_down 5
-      pdf.text "Generated on #{Time.current.strftime('%B %d, %Y at %I:%M %p')}", align: :center
-    end.render
-  end
-end