fix: trashed backup before replace, byte-exact meta copy, partial rollback

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7

src/Integrations/WordPress/Status/ReplaceFailed.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Integrations\WordPress\Status;
+
+use RuntimeException;
+use Throwable;
+
+/**
+ * Thrown by PostCloner::replace(). $parts lists the parts of the original replace()
+ * had started to write (post, meta, terms) – only those need to be restored.
+ */
+final class ReplaceFailed extends RuntimeException
+{
+    /** @param list<string> $parts */
+    public function __construct(public readonly array $parts, Throwable $previous)
+    {
+        parent::__construct($previous->getMessage(), 0, $previous);
+    }
+}