refactor: Convert ticket views to use only Tailwind CSS

- Rewrite ticket show view to use pure Tailwind CSS classes
- Update color scheme from gray-* to slate-* for modern look
- Replace indigo gradients with violet for better consistency
- Enhance spacing, typography, and visual hierarchy
- Add ticket_view route and controller action for PDF-like display
- Implement responsive QR code display with proper sizing
- Update status badge colors for better semantic meaning
- Improve accessibility with better button layouts and focus states

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

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

config/routes.rb

@@ -61,6 +61,7 @@ Rails.application.routes.draw do
   get   "tickets/checkout/events/:slug.:id", to: "tickets#checkout", as: "ticket_checkout"
   post  "tickets/retry/events/:slug.:id",    to: "tickets#retry_payment", as: "ticket_retry_payment"
   get   "tickets/:ticket_id",                to: "tickets#show", as: "ticket"
+  get   "tickets/:ticket_id/view",           to: "tickets#ticket_view", as: "ticket_view"
   get   "tickets/:ticket_id/download",       to: "tickets#download_ticket", as: "download_ticket"
 
   # === Promoter Routes ===