fix: typed write failures, template rollback, parent and term cleanup

WriteFailed maps to lit_write_failed / lit_partial_write (partial writes are
logged with result partial); old template read before the update; row marker
set before wp_update_post; created terms deleted on rollback; parent must be a
readable non-descendant of a hierarchical type; featured image must be
readable; snapshot keeps empty values; meta comparison after sanitize_meta;
follow-up failures (listener, change log) only add warnings.

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

tests/Unit/Abilities/FollowUpTest.php

@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Tests\Unit\Abilities;
+
+use LIT\MCP\Abilities\FollowUp;
+use LIT\MCP\Tests\Unit\TestCase;
+use RuntimeException;
+
+final class FollowUpTest extends TestCase
+{
+    public function testReturnsTheResultOfASuccessfulStep(): void
+    {
+        $warnings = [];
+
+        self::assertSame(7, FollowUp::run(static fn (): int => 7, 'ctx', 'Warnung', $warnings));
+        self::assertSame([], $warnings);
+    }
+
+    public function testAFailingStepIsLoggedAndBecomesAWarning(): void
+    {
+        $log = (string) tempnam(sys_get_temp_dir(), 'lit-mcp-log');
+        $previous = ini_set('error_log', $log);
+        $warnings = ['alt'];
+
+        try {
+            $result = FollowUp::run(
+                static function (): void {
+                    throw new RuntimeException('hook kaputt');
+                },
+                'lit/content-create after_save',
+                'Warnung',
+                $warnings
+            );
+        } finally {
+            ini_set('error_log', (string) $previous);
+        }
+
+        self::assertNull($result);
+        self::assertSame(['alt', 'Warnung'], $warnings);
+        self::assertStringContainsString('lit/content-create after_save', (string) file_get_contents($log));
+        self::assertStringContainsString('hook kaputt', (string) file_get_contents($log));
+        unlink($log);
+    }
+}