New design for post-purchase extension

# Post-purchase extension

There are two parts to the extension:
- Create wallet page
- Wallet link page

Note: All of these designs need to use these [elements](https://shopify.dev/docs/api/checkout-extensions/post-purchase/components)
(annoying, yes but there's no other choice)

## Create wallet page

**Current design:**

**Requirements:**

- There needs to be a message that tells the user that they have received a token from Greenstand and congratulations
- There needs to be a short explanation of Greenstand, and what happens to the user
- There is a message that says "Powered by Greenstand"
- There is a checkbox that says "I opt in/I agree to this program"
- There is an input to fill in the wallet name
- Errors are in red text below the input field
- There are two buttons - One in primary color that says "Create wallet" and one in secondary color that says "No thanks"

**Additional information:**

- Is there anything else we might need here?

## Wallet link page

**Current design:**

**Requirements:**

- There needs to be a link that brings the user to the wallet
- There needs to be a button to move on

**Additional information:**

- I haven't added much here, is there anything else that would make it look better? (headers, images, etc.)

Start with the Shopify post-purchase extension components linked in the issue and review the two supplied designs. Implement the Create wallet and Wallet link pages using those elements, including the listed messages, opt-in checkbox, wallet-name validation, actions, and wallet link. Done means both pages meet the requirements and the open design questions have been resolved.

Written by the indexing model from the issue text.