Refund eBay Update

Companion to refundEbayShipping.php. Displays shipping refunds recorded in eBay Seller Hub that still need to be reconciled when the deduction posts to the merchant Managed Payments account.

• Enter Today's Payout ID from the current eBay payout batch before submitting any ledger action.
• Search prior payout rows by buyer name to reverse an existing payout when issuing a refund.
• Manually add refund ledger rows when order details are known outside the pending grid.
• Adjust refund amounts and click Update Managed Payments to mark rows processed in pd_ebay_refund_shipping, insert the negative payout row, and move the OpenCart order to Refunded status.

Upstream: refundEbayShipping.php creates pending rows. Downstream tables: pd_ebay_payouts, pd_ebay_refund_shipping, oc_order, oc_order_history.