fix: name the WordPress revision screen for library and layout revisions (audit L3)

lit/revision-restore takes only content types, so a write to a library entry
or a Theme Builder layout now answers with restore_url (wp-admin
revision.php for its revision_id), also per page in lit/divi-replace-text.
The guides and readme no longer present lit/revision-restore as the way back
for these types.

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

tests/Support/LibraryFixtures.php

@@ -85,6 +85,7 @@ final class LibraryFixtures
             static fn (string $key, string $value, string $url): string => $url . '&' . $key . '=' . $value
         );
         Functions\when('get_preview_post_link')->justReturn('https://kunde.test/?page_id=7&preview=true');
+        Functions\when('admin_url')->alias(static fn (string $path = ''): string => 'https://kunde.test/wp-admin/' . $path);
     }
 
     /** A store that answers isGlobal()/layoutType() from ITEMS (no database). */