Implement Coinbase Custody: edge cases

[theblockstalk]

Acceptance criteria

• [ ] implement edge cases

Edge cases:

1. doesn't pay correct amount (not enough) - give use 5 days to fix, or cancel the order. tell user to pay the final amount (in the web app, or via email)
2. doesn't pay correct amount (too much) - then refund the user the extra amount immediately. confirm this by email as well
3. doesn't pay correct amount (not enough) and the LEOS Agreement contract has expired (currently 5 days) - refund immediately and let user know by email
4. Update the Docuseal LEOS Agreement contract expiration time from 1 day to 5 days. This is to implement a process to refund users who have not paid the correct amount.

Resources:

• https://docs.cdp.coinbase.com/prime/docs/welcome/
• https://www.coinbase.com/prime/custody

Definition of done:

• [ ] Create a DB and API plan before starting implementation