Prepare v0.1.0 release - code review and documentation updates

- Conducted comprehensive security and best practices review
- Fixed VersionManager null format handling for attachment updates
- Improved input sanitization in AdminController for page context checks
- Updated README.md with complete feature documentation
- Updated CHANGELOG.md with 0.1.0 release notes
- Updated translations (.pot, .po, .mo files) to version 0.1.0
- Bumped version to 0.1.0 in plugin header and constant

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/Product/VersionManager.php

@@ -167,8 +167,20 @@ class VersionManager
         }
 
         if ($attachmentId !== null) {
-            $data['attachment_id'] = $attachmentId > 0 ? $attachmentId : null;
-            $formats[] = $attachmentId > 0 ? '%d' : null;
+            if ($attachmentId > 0) {
+                $data['attachment_id'] = $attachmentId;
+                $formats[] = '%d';
+            } else {
+                // Set to NULL using raw SQL instead of adding to $data
+                global $wpdb;
+                $tableName = Installer::getVersionsTable();
+                $wpdb->query(
+                    $wpdb->prepare(
+                        "UPDATE {$tableName} SET attachment_id = NULL WHERE id = %d",
+                        $versionId
+                    )
+                );
+            }
         }
 
         if (empty($data)) {