mymi14s/frappe_paystack ? reverse-engineered prompt

Build me a Frappe and ERPNext app that adds Paystack as a payment gateway and fits naturally into the existing sales, POS, and customer portal flows.

I want it to let customers pay sales invoices, sales orders, POS invoices, and dunning notices, either in full or part. It should support both an inline Paystack popup and a hosted checkout page, send payment links by email, show a QR code on the invoice, and give customers a simple place to see their payments, refunds, and receipts. It should also handle saved cards, automatic refunds when credit notes are made, subscription invoice charging, and payout reconciliation so the books match what Paystack actually sends.

Please include the setup screen for company specific keys and accounts, webhook handling, validation, and a dashboard or reports for monitoring payments and mismatches. If you need current Paystack or Frappe docs, look them up online as you go.