feat: field validation, term resolution, post guard and revision points

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

src/Integrations/WordPress/RevisionPoint.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Integrations\WordPress;
+
+/**
+ * Restore point before a change (spec §2 principle 7): WordPress stores the
+ * current state as a revision (only if it differs from the newest one) and the
+ * newest revision ID is returned as revision_id of the ToolResult.
+ * Note: revisions cover title, content and excerpt; meta and terms are not revisioned.
+ */
+final class RevisionPoint
+{
+    public static function capture(int $postId): ?int
+    {
+        wp_save_post_revision($postId);
+
+        return self::latest($postId);
+    }
+
+    public static function latest(int $postId): ?int
+    {
+        $revisions = wp_get_post_revisions($postId, ['posts_per_page' => 1]);
+        $newest = is_array($revisions) ? reset($revisions) : false;
+
+        return is_object($newest) ? (int) $newest->ID : null;
+    }
+}