Takes a Member doc + a normalized Helcim transaction and inserts a
Payment row if helcimTransactionId is unseen. Maps helcim status
paid→success, refunded→refunded, failed→failed; skips 'other'.
opts.paymentType overrides the cadence fallback for mid-flight cadence
changes. opts.sendConfirmation triggers a Resend payment-confirmation
email ONLY on new inserts — swallows send failures so email trouble
cannot break the upstream payment flow.
The Resend template lives in server/emails/paymentConfirmation.js. It
is CRA-safe (charity name + 'not an official donation receipt / tax
receipts available later in 2026' disclaimer) so it can be used in
either Task 8 branch without copy changes.