feat: batch media metadata updates and delete with usage check

lit/media-update validates the whole batch first (edit_post, lengths, optional
modified lock) and restores already written items when a write fails midway.
lit/media-delete requires confirm, refuses used media without force and
reports refused deletes as write_failed.

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

tests/Unit/Integrations/Media/MediaPresenterTest.php

@@ -45,6 +45,7 @@ final class MediaPresenterTest extends TestCase
         self::assertSame('Porträt', $summary['alt']);
         self::assertSame(1600, $summary['width']);
         self::assertSame(123456, $summary['filesize']);
+        self::assertSame('2026-09-25 08:00:00', $summary['modified']);
     }
 
     public function testFullListsSizesAndUsagesAndCopesWithMissingMetadata(): void