fix: never publish a missed schedule, refuse trashed posts, fail on meta read errors

- PostGuard::editable() refuses trashed entries unless the caller opts in
  (content-get, revisions-list, post-trash); publish/schedule/unpublish/update/
  restore/duplicate/replace now refuse them.
- PostGuard::statusStable(): content-update, revision-restore and
  replace-with-copy refuse a future post whose date has passed (any save would
  publish it); the content-update rollback and PostCloner row writes re-check.
- PostCloner::ownMeta() treats a failed SELECT as an error; replace() reads the
  copy before its first write.
- replace-with-copy needs create_posts (backup clone) and reports backup_id in
  write_failed/partial_write.

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

tests/Unit/Integrations/WordPress/Status/PostPublishAbilityTest.php

@@ -74,6 +74,16 @@ final class PostPublishAbilityTest extends TestCase
         self::assertStringContainsString('bereits veröffentlicht', $result['summary']);
     }
 
+    public function testATrashedPostIsRefused(): void
+    {
+        $this->stubPost(['post_status' => 'trash']);
+        Functions\expect('wp_update_post')->never();
+
+        $result = $this->ability(Mockery::mock(ChangeLog::class))->execute(['post_id' => 5]);
+
+        self::assertSame('lit_validation_failed', $result->get_error_code());
+    }
+
     public function testPermissionNeedsPublishRights(): void
     {
         $this->stubPost(['post_status' => 'draft']);