refactor: PostRow::update and PostGuard::assertNoMissedSchedule (M5)

- PostRow::update(id, columns, failure) / ::save(): the slashed wp_update_post of
  internal row writes, refusals as RuntimeException '<failure>: <why>'. Used by
  ContentUpdate::restoreRow, PostCloner::updateRow, MediaMetaWriter apply/restore.
- PostGuard::assertNoMissedSchedule(postId, message) replaces the re-read + check in
  ContentUpdate::restoreRow, PostCloner and DiviSaver::restore (DiviSaver keeps its
  own kses window; M4).
- PostCloner::restore uses Rollback::attempt.
Log messages unchanged.

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

src/Integrations/WordPress/Status/PostCloner.php

@@ -4,8 +4,10 @@ declare(strict_types=1);
 
 namespace LIT\MCP\Integrations\WordPress\Status;
 
+use LIT\MCP\Abilities\Rollback;
 use LIT\MCP\Abilities\WriteFailed;
 use LIT\MCP\Integrations\WordPress\PostGuard;
+use LIT\MCP\Integrations\WordPress\PostRow;
 use RuntimeException;
 use Throwable;
 use WP_Error;
@@ -143,14 +145,7 @@ class PostCloner
             'meta' => fn () => $this->replaceMeta($postId, $snapshot['meta']),
             'terms' => fn () => $this->setTerms($postId, $snapshot['terms']),
         ];
-        $failures = [];
-        foreach (array_intersect_key($steps, array_flip($parts)) as $step) {
-            try {
-                $step();
-            } catch (Throwable $e) {
-                $failures[] = $e->getMessage();
-            }
-        }
+        $failures = Rollback::attempt(...array_values(array_intersect_key($steps, array_flip($parts))));
 
         if ($failures !== []) {
             throw new RuntimeException('Restore incomplete: ' . implode('; ', $failures));
@@ -225,11 +220,7 @@ class PostCloner
     private function updateRow(int $postId, array $columns): void
     {
         $this->assertNoMissedSchedule($postId);
-        $result = wp_update_post(wp_slash(array_merge(['ID' => $postId], $columns)), true);
-        if ($result instanceof WP_Error || ! $result) {
-            $message = $result instanceof WP_Error ? $result->get_error_message() : 'unknown error';
-            throw new RuntimeException(sprintf('Post %d could not be updated: %s', $postId, $message));
-        }
+        PostRow::update($postId, $columns, sprintf('Post %d could not be updated', $postId));
     }
 
     /**
@@ -239,13 +230,10 @@ class PostCloner
      */
     private function assertNoMissedSchedule(int $postId): void
     {
-        $post = get_post($postId);
-        if ($post instanceof WP_Post && PostGuard::missedSchedule($post)) {
-            throw new RuntimeException(sprintf(
-                'Post %d not written: saving it now would publish a missed schedule.',
-                $postId
-            ));
-        }
+        PostGuard::assertNoMissedSchedule(
+            $postId,
+            sprintf('Post %d not written: saving it now would publish a missed schedule.', $postId)
+        );
     }
 
     /**