Summary

This PR completes the human-usable GNU Taler refund lifecycle in Ledger. It makes Taler refund URIs persistent and customer-facing, adds refund history and email delivery, exposes a public wallet handoff page, and adds scheduled refund verification so invoices only progress from pending refund states once the Taler wallet has picked up the refund.

What Changed

• Added refund history surfaces so issued Taler refund URIs remain accessible after the initial modal closes.
• Added customer-facing HTTPS Taler refund handoff with wallet metadata, open-wallet action, QR/copy fallback, and public-safe refund data.
• Added email delivery for Taler refund links using a Ledger notification and mail template.
• Updated invoice refund behavior so Taler refunds enter refund_pending or partial_refund_pending until wallet acceptance is confirmed.
• Added ledger:taler:verify-refunds, scheduled every 15 minutes, to poll Taler Merchant Backend order status using refund_pending, refund_taken, and cumulative refund amounts.
• Added a manual Verify Status action from invoice refund history for immediate operator testing.
• Improved Taler driver support for refund status polling and query-aware order status checks.
• Updated internal routes, auth schema, invoice controller responses, payment/refund listeners, gateway credential diagnostics, and focused static tests.

Validation

• php -l passed for touched PHP files.
• npx eslint addon/controllers/billing/invoices/index/details.js addon/components/modals/refund-history.js passed.
• npm run lint:hbs -- addon/components/modals/refund-history.hbs addon/components/modals/refund-result.hbs addon/components/customer-taler-refund.hbs addon/components/customer-invoice.hbs exited successfully, with the existing no-down-event-binding configuration warning still printed.
• git diff --check passed.
• Focused Pest slice could not run locally because Pest is not installed in this checkout: Unable to find Pest. Run composer install first.

Notes

The scheduler is intentionally no-op friendly: if no active Taler gateways or pending Taler refunds exist, it exits cleanly. The command can also be run manually with php artisan ledger:taler:verify-refunds or scoped to one refund with --refund=<gateway_transaction_id>.