Translate pages, areas, menus, forms and posts field by field instead of rebuilding them

A site can have further languages (Settings → Languages). A page is built once; each language
adds only its texts, keyed by the stable block IDs, plus its own address under /en/… (ADR 111,
document schema v27, migration 20261009000100 for page_translation).

- Editor: DE | EN switch, a list of all texts with original, state (missing, translated,
  original changed) and filter; structure stays with the main language. Undo, drafts,
  publishing and revisions cover all languages at once.
- Website: /en and translated slugs, lang, canonical, hreflang with x-default, og:locale,
  sitemap; links to translated pages follow the language; a language switch block.
- Header, footer and linked sections translate the same way; menu entries carry labels per
  language; fixed template texts come from a small dictionary.
- Forms: labels, help, options, button and success message per language; messages and the
  step script speak the language, the submission and the email stay in the main language.
- Posts, archives, category names, consent text and the 404 page follow the language.
- Single-language sites see none of it and never touch the new table.

The forms administration becomes an overview with one row per form and its own edit page;
fields are one line each with details collapsed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/TestSchema.php

@@ -22,6 +22,7 @@ use DoctrineMigrations\Version20260914000100;
 use DoctrineMigrations\Version20260915000100;
 use DoctrineMigrations\Version20260916000100;
 use DoctrineMigrations\Version20260917000100;
+use DoctrineMigrations\Version20261009000100;
 use Psr\Log\NullLogger;
 
 /**
@@ -55,6 +56,7 @@ final class TestSchema
             Version20260915000100::class,
             Version20260916000100::class,
             Version20260917000100::class,
+            Version20261009000100::class,
         ] as $migration) {
             (new $migration($db, new NullLogger()))->up($schema);
         }