style: summary and user info 2026 - #121

Description

Updates the Summary / Confirm Details step and User Registration Info UI to align with the PyCon 2026 Figma specifications while maintaining existing form handling, field names, and validation logic.

Figma: https://www.figma.com/design/7T8qFvssYvyM2M5gI2FoXi/PyCon-2026?node-id=104-2&p=f&t=5Kq6JgpowVBgjAUi-0

Changes

• Summary Step (SummaryStep.tsx): Replaced the legacy summary layout with structured cards for personal information, ticket details, promotions, and order summary. Added required consent checkboxes.
• Components (SummaryCard.tsx): Added reusable card and row components for structured detail display.
• Registration Headers (Register.tsx, RegistrationSteps.ts): Added step category and description metadata with responsive header styling.
• Form Integrity: Retained all existing react-hook-form field names, state management, and validation handlers.

Acceptance Criteria Checklist

• UI matches Figma design specifications.
• Existing summary information displays correctly without data loss.
• Form item name props remain unchanged.
• Unchecked mandatory consent checkboxes prevent form submission.
• Responsive layout verified across Mobile (<768px), Tablet (>=768px), and Desktop (>=1024px).

Verification

• Unit tests: All test suites passing (npm run test:unit).
• Manual testing: Verified data persistence across steps, validation triggers, and successful submission flow.