Initial commit: ws_vatcheck at v1.0.3

Includes the fix for the GR/EL VAT prefix bug that broke exemption for
every Greek VAT number (in_array-on-values vs array_key_exists in
CacheTaxManager/VatNumber, plus the missing use import in
EuValidatorAdapter). Adds IMPROVEMENTS.txt with a checklist of features
adopted from comparing against the vatchecker module (offline-fallback
policy, failure logging, company-name check, configurable EU country
list, per-product exclusion, GB/XI mapping, AJAX live validation,
address-priority strategy).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

vendor/autoload.php

@@ -0,0 +1,22 @@
+<?php
+
+// autoload.php @generated by Composer
+
+if (PHP_VERSION_ID < 50600) {
+    if (!headers_sent()) {
+        header('HTTP/1.1 500 Internal Server Error');
+    }
+    $err = 'Composer 2.3.0 dropped support for autoloading on PHP <5.6 and you are running '.PHP_VERSION.', please upgrade PHP or use Composer 2.2 LTS via "composer self-update --2.2". Aborting.'.PHP_EOL;
+    if (!ini_get('display_errors')) {
+        if (PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg') {
+            fwrite(STDERR, $err);
+        } elseif (!headers_sent()) {
+            echo $err;
+        }
+    }
+    throw new RuntimeException($err);
+}
+
+require_once __DIR__ . '/composer/autoload_real.php';
+
+return ComposerAutoloaderInitf0c36081834639cb4575b2393bd0885d::getLoader();