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/ph-7/eu-vat-validator/composer.json

@@ -0,0 +1,45 @@
+{
+  "name": "ph-7/eu-vat-validator",
+  "description": "A simple and clean PHP class that validates EU VAT numbers against the central ec.europa.eu database (using the official europa API).",
+  "keywords": [
+    "eu vat",
+    "vat number",
+    "validate eu vat",
+    "validate vat number",
+    "vat validator",
+    "vat number validator",
+    "vat",
+    "tva",
+    "tva number",
+    "validation",
+    "validator",
+    "VIES"
+  ],
+  "type": "library",
+  "homepage": "https://pierrehenry.be",
+  "license": "GPL-3.0-or-later",
+  "authors": [
+    {
+      "name": "Pierre-Henry Soria",
+      "email": "hi@ph7.me",
+      "homepage": "https://github.com/pH-7/eu-vat-validator",
+      "role": "Software Engineer"
+    }
+  ],
+  "require": {
+    "php": ">=7.1.0",
+    "ext-soap": "*"
+  },
+  "require-dev": {
+    "phpunit/phpunit": "^7.5",
+    "phake/phake": "^3.1"
+  },
+  "autoload": {
+    "psr-4": {
+      "PH7\\Eu\\": "src"
+    }
+  },
+  "scripts": {
+    "test": "vendor/bin/phpunit"
+  }
+}