one-pipe-system/openspec/changes/update-refund-order-voucher/tasks.md

1. Implementation

• 1.1 Update refund order creation request type to include required refund_voucher_key: string.
• 1.2 Add refund voucher image upload to the refund order creation form using /storage/upload-url, storing the returned file key.
• 1.3 Validate that refund voucher is uploaded before allowing refund order creation.
• 1.4 Submit refund_voucher_key in the create refund order payload.
• 1.5 Add a list operation to view the refund voucher when refund_voucher_key exists, matching the existing order list payment voucher behavior.
• 1.6 Show the refund voucher directly in refund order details when refund_voucher_key exists.
• 1.7 Verify create, list preview, and detail display flows manually or with existing tests.