- Backend refund endpoint: allow refunds on paid invoices without stripePaymentIntentId (manual refund path)
- Backend GET /invoices/🆔 inline fetch cardLast4 + paymentStatus from Stripe when stripePaymentIntentId present
- Frontend: show Refund button on all paid invoices for managers (not just Stripe-backed ones)
- Seed: add stripePaymentIntentId (pi_test_*) to ~20% of paid invoices for Stripe-path testing
cc @cpfarhood