[FEATURE] describe actual state of async payment flow

[mkucmus]

Description

• describe the current state
• report the bugs
• find solutions

Use Case

• there are still hidden parts in async payment process like what would happen in case of fail or unfinished happy path

Proposed Solution

No response

Alternatives Considered

No response

Additional Context

No response

[mkucmus]

issues found:

• no feedback about failed transaction after redirection from finalize-payment route - there is no info what went wrong, customer is just redirected back to frontend app URL according to handlePayment URL defined, with no details
• the async flow is not fully headless, the finalizeTransaction action takes place in storefront context
• sometimes the payment handler does not handle additional parameters required to finish transaction, like success token for payment intent for credit cards

[BrocksiNet]

Push it :)