[TechTix]: Update Ticket Selection Step

[seangaaab]

Figma / Design Link

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

Description / Objective

• To update basic information step UI to match this year's design
• Copy existing form handling and ensure that form still works as expected.
• Only styles/structure should be updated.
• TechTix –frontend/src/pages/client/pycon/register/steps/TicketSelectionStep.tsx

Responsive Design Requirements

• Mobile (Small screens, <768px)
• Tablet (Medium screens, >=768px)
• Desktop (Large screens, >=1024px)

Acceptance Criteria

• The UI implementation matches the figma design
• Exclude the following ticket types: "Kodigo", "Kumpanya"
• Exclude the "Premium Shirt" Field.
• Retain the discounted price display. Similar to what was implemented now. You may utilize this by updating the "price" and "originalPrice" of the tickets. The price shows the current price, and the original price is the base price (undiscounted) of the ticket.

- The `name` prop of each `` should still be the same. No changes. If there are any questions regarding the mapping of the names to the design, please ask @seangaaab - Clicking the "Next" button should trigger form errors if there are empty/invalid form values. If there are no form errors, the "Next" button should navigate the user to the next step

NOTES: When creating an event, follow these steps to add the ticket types:

1. Turn on the "Is this a paid event?" switch and add any price
2. Turn on the "Will there be ticket tiers?" switch.
3. Add two ticket types. Their names should EXACTLY be "coder" and "kasosyo"