fix(exchange): show unknown-outcome auto-exchanges as needing reconciliation in the notification email #1055

Found during the independent review of #1053, which bumps cloud-commitments-go to 3def3f8.

Since go#497/#499, an auto-exchange whose accept outcome is unknown stays in AutoExchangeResult.Failed with OutcomeUnknown=true. go keeps the ledger record non-failed, so it still counts against the daily cap, and the run halts (go pkg/exchange/auto.go:577-584).

The platform ignores the flag. buildExchangeNotificationData (internal/server/handler_ri_exchange.go:201-224) copies only Error, so the notification email lists the exchange as failed. The error text says "purchase outcome unknown", so the email is not wrong, but it does not tell the operator to reconcile before acting.

Ask: carry OutcomeUnknown into the notification data, and render unknown-outcome exchanges in their own "verify in AWS / reconcile" group, separate from real failures. Add a test with an unknown-outcome result.