[mpge]

TL;DR: Adds optional one-way records of completed Shopify payments and refunds to Inventoros' payment ledger, with transaction IDs preventing duplicates. It does not charge or refund customers.

Successful sales/captures and refunds use the audited core import API; pending/failed transactions and authorizations create no receipts. Currencies must match, active manual entries require reconciliation, voids stay voided, and refunds cannot exceed recorded receipts. Historical/cancelled orders are supported without stock changes or historical payment announcements. Current-order announcements wait until the complete order, ledger and mapping commit. Refund webhooks refresh the complete transaction snapshot; histories beyond 100 transactions or incomplete responses stop for manual review.

Off by default. Requires Inventoros/Inventoros#305 for payment imports; older cores retain the existing sync features and show an upgrade hint. Enabling the option retests the connection and registers refund notifications.

Stacked on #5; merge #3, #4 and #5 first. Merge core Inventoros/Inventoros#305 before enabling payments. The setup guide, release version and changelog are updated.

Validation: the complete combined stack passes 150 tests / 857 assertions on PostgreSQL. The MySQL suite passes 149 tests / 856 assertions, with the final token-renewal regression also passing separately (6 authentication tests / 30 assertions). The final combined shipment/import stack passes 162 tests / 900 assertions on SQLite, including console-handler compatibility. Both 1.3.0 and 1.4.0 release ZIPs install, activate, reactivate and uninstall through the real installer in an isolated database. Runtime UI builds pass. Requests use fakes; no live store was changed.

GitHub-hosted CI cannot start because GitHub reports failed account payments or a spending-limit restriction. No build steps ran; local checks above cover the changes.