fix: admin UI review round 1 (S47) - Art labels, usage only on success, result fallback

- Art column: only lit/media-delete and lit/divi-delete say "löscht",
  lit/post-trash "Papierkorb", other destructive tools "überschreibt".
- ConnectionUsage records only responses with status < 400 (mcp-oauth answers
  auth failures with WP_REST_Response 401, not WP_Error).
- Log result column: translated "unbekannt" instead of the raw value.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/Unit/Admin/Fixtures/HttpResponses.php

@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+// Minimal stand-ins for WordPress' response classes (only the status part), for ConnectionUsageTest.
+
+if (! class_exists('WP_HTTP_Response')) {
+    class WP_HTTP_Response
+    {
+        public function __construct(public mixed $data = null, public int $status = 200)
+        {
+        }
+
+        public function get_status(): int
+        {
+            return $this->status;
+        }
+    }
+}
+
+if (! class_exists('WP_REST_Response')) {
+    class WP_REST_Response extends WP_HTTP_Response
+    {
+    }
+}