Release 1.10.55

Fixes checkout-time SoftOne exports when pending orders are not ready yet.\n\n- Skips SoftOne export attempts for pending checkout orders, even if a site filter adds pending to the export statuses.\n- Skips incomplete orders that have no line items, billing email, or customer name instead of creating repeated missing TRDR notes/retries.\n- Adds a regression test for order export readiness guards.\n\nValidated with:\n- php -l includes/class-softone-order-sync.php\n- php -l includes/class-softone-api-client.php\n- php -l softone-woocommerce-integration.php\n- php -l tests/order-export-readiness-test.php\n- php tests/order-export-readiness-test.php\n- php tests/legacy-greek-json-decoding-test.php