Increase fallback coverage for mint character

[carlos-kryha]

Description

Review frontend error handling for the mint flow and ensure the frontend does not get "stuck" when minting a character

Validation and error handling

The mint flow starts with the "Create character" input form, which takes a string as input (to pick a character name) and performs the following validation (showing errors when present):

1. Name adheres to the guidelines set on contract (special characters, length requirements, etc)
2. Name is unique
3. User has enough IST available to mint

If no validation errors are present, the mint button is enabled. Pressing mint will form the mint proposal based on the input and trigger Agoric's addOffer method, which also accepts a callback set up to track offer updates.

Should anything error out in the process of forming and executing addOffer the error will be caught and a generic error will be displayed to the user.

If addOffer is triggered correctly, the following offerStatus updates are handled:

1. seated: indicates the offer was successfully parsed by the contract? (I couldn't find documentation around this, so this definition is from experience). We start a timer which will display an error to the user in case no further offer updates are received within 30s (typically the mint offer returns the "success" status within 10s of it being seated)
2. error: indicates an error occurred while minting. A generic error is displayed prompting the user to try again
3. accepted: indicates mint call was successful. We clear the timer set to error if the call takes too long. We do not yet give the user confirmation, as we want to wait until the new character is accessible from the user's wallet

Finally, we have a useEffect in the create-character component that listens for updates in the user's wallet and shows confirmation to the user once the newly minted character is correctly parsed by KREAd's frontend