Rename module to AdminOrderColumns and add thumbnail removal

Major changes:
- Renamed module from OrderItemsCustom to AdminOrderColumns for clarity
- Added CSS to hide product thumbnails in order items view
- Updated all namespaces from Shopkeeper\OrderItemsCustom to Shopkeeper\AdminOrderColumns
- Updated composer package name to shopkeeper/module-admin-order-columns
- Bumped version to 1.1.0
- Added layout XML and CSS files for thumbnail removal
- Updated all documentation and installation instructions

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

composer.json

@@ -1,8 +1,8 @@
 {
-    "name": "shopkeeper/module-order-items-custom",
-    "description": "Customizes order item columns in Magento admin - removes tax columns and adds cost column with clickable product links",
+    "name": "shopkeeper/module-admin-order-columns",
+    "description": "Customizes order item columns in Magento admin - removes tax columns, adds cost column with clickable product links, and hides product thumbnails",
     "type": "magento2-module",
-    "version": "1.0.0",
+    "version": "1.1.0",
     "license": [
         "OSL-3.0",
         "AFL-3.0"
@@ -26,7 +26,7 @@
             "registration.php"
         ],
         "psr-4": {
-            "Shopkeeper\\OrderItemsCustom\\": ""
+            "Shopkeeper\\AdminOrderColumns\\": ""
         }
     }
 }