A quote with no explicit payment timing falls back to a single after_delivery
installment. spawnInstallmentInvoices marked those 'pending_delivery' even in
hold mode, so the booking flow's send_document -> sendInvoice threw 'Cannot send
invoice with status pending_delivery', the run failed, and no invoice email went
out (the symptom: approve the quote->invoice flow, receive nothing).
In hold mode the flow's review gate + explicit send_document IS the delivery
release, so a held invoice is always 'scheduled' (editable + sendable) regardless
of trigger; scheduled_send_at stays null so the scheduler never auto-sends it.
Non-hold after_delivery invoices keep 'pending_delivery' as before.
Adds a regression test (default after_delivery term -> draft -> scheduled+null).
Luca
882cfc0661