Rename package to shopkeeper/module-pdfing-po

- Updated package name to follow naming conventions

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

composer.json

@@ -1,5 +1,5 @@
 {
-    "name": "shopkeeper/pdfingpo",
+    "name": "shopkeeper/module-pdfing-po",
     "description": "Magento 2 module to allow staff to print PDF PO documents using Amasty's PDF Customizer templates and Amasty Custom Order Attributes.",
     "type": "magento2-module",
     "version": "1.0.0",