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/Content/ContentGetAbilityTest.php

@@ -29,6 +29,19 @@ final class ContentGetAbilityTest extends TestCase
         self::assertSame(['id' => 5], $ability->execute(['post_id' => 5]));
     }
 
+    public function testATrashedPostCanStillBeRead(): void
+    {
+        $post = new WP_Post(['ID' => 5, 'post_type' => 'page', 'post_status' => 'trash']);
+        Functions\when('get_post')->justReturn($post);
+        Functions\when('current_user_can')->justReturn(true);
+        $schema = Mockery::mock(ContentSchema::class);
+        $schema->allows('isManaged')->andReturn(true);
+        $presenter = Mockery::mock(PostPresenter::class);
+        $presenter->expects('full')->with($post)->andReturn(['id' => 5]);
+
+        self::assertSame(['id' => 5], (new ContentGetAbility($schema, $presenter))->execute(['post_id' => 5]));
+    }
+
     public function testMissingPostIsNotFound(): void
     {
         Functions\when('get_post')->justReturn(null);