Uiux/booking guest vs signin - #494

Closes #231

Summary

This PR introduces an intermediate branching step in the booking flow before checking out. It presents users with a clear choice to continue as a Guest, Sign In, or Create an Account.

By detailing the tradeoffs for each path upfront using feature comparisons (checkmarks and warnings), we ensure users are aware of the benefits of an authenticated session (e.g., booking history, saved preferences) versus a wallet-only guest session. We also added a "why sign in?" popover for additional context. The path transitions elegantly to the confirm step upon selection without discarding any prior context (e.g., discount codes or gift details).

Design Review Checklist

♿ Accessibility

• Contrast ratios meet WCAG 2.1 AA (4.5:1).
• Keyboard navigation is logical and focus rings are visible.
• Semantic HTML and ARIA labels are used correctly (e.g., aria-label on the popover icon).

📱 Responsive

• Layout is mobile-first and works on all breakpoints.
• Above-the-fold content is optimized for laptop viewports.

⚙️ States & Tokens

• Loading, empty, and error states are handled.
• Design tokens (spacing, helper-text classes) are followed.

Screenshots / Record

Nil

Testing

• npm run lint passes
• Manual keyboard/screen-reader test (verified tab ordering and interactions for the new cards and popover inside the modal context)