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>

src/Content/MenuRepository.php

@@ -95,7 +95,11 @@ final class MenuRepository
      */
     private ?array $pages = null;
 
-    public function resolve(array $items, string $currentPath, string $locale = 'de'): array
+    /**
+     * @param string|null $language eine weitere Sprache (ADR 111): Einträge zeigen dann ihre
+     *                              Beschriftung in dieser Sprache, sofern sie eine haben
+     */
+    public function resolve(array $items, string $currentPath, string $locale = 'de', ?string $language = null): array
     {
         if (null === $this->pages) {
             $this->pages = [];
@@ -104,15 +108,16 @@ final class MenuRepository
             }
         }
 
-        return $this->resolveLevel($items, $this->pages, $currentPath, $this->settings->homePath());
+        return $this->resolveLevel($items, $this->pages, $currentPath, $this->settings->homePath(), $language);
     }
 
-    private function resolveLevel(array $items, array $pages, string $currentPath, string $homePath): array
+    private function resolveLevel(array $items, array $pages, string $currentPath, string $homePath, ?string $language = null): array
     {
         $links = [];
         foreach ($items as $item) {
-            $children = $this->resolveLevel($item['children'] ?? [], $pages, $currentPath, $homePath);
-            $label = $item['label'] ?? '';
+            $children = $this->resolveLevel($item['children'] ?? [], $pages, $currentPath, $homePath, $language);
+            $translated = null === $language ? '' : trim((string) ($item['labels'][$language] ?? ''));
+            $label = '' !== $translated ? $translated : ($item['label'] ?? '');
             if ('page' === $item['type']) {
                 $page = $pages[$item['pageId']] ?? null;
                 if (null === $page || null === $page['published_revision_id']) {
@@ -159,6 +164,18 @@ final class MenuRepository
             if (!is_array($item) || !is_string($item['label'] ?? null) || '' === trim($item['label']) || mb_strlen($item['label']) > 80) {
                 throw new InvalidMenu('Jeder Eintrag braucht eine Beschriftung mit höchstens 80 Zeichen.');
             }
+            // Beschriftungen in weiteren Sprachen (ADR 111): je Sprache ein Text, wie die
+            // Beschriftung höchstens 80 Zeichen. Eine leere zeigt die Beschriftung der Hauptsprache.
+            if (array_key_exists('labels', $item)) {
+                if (!is_array($item['labels']) || ([] !== $item['labels'] && array_is_list($item['labels']))) {
+                    throw new InvalidMenu('Die übersetzten Beschriftungen sind ungültig.');
+                }
+                foreach ($item['labels'] as $code => $text) {
+                    if (!is_string($code) || !isset(Languages::CATALOG[$code]) || !is_string($text) || '' === trim($text) || mb_strlen($text) > 80) {
+                        throw new InvalidMenu('Eine übersetzte Beschriftung hat höchstens 80 Zeichen und gehört zu einer bekannten Sprache.');
+                    }
+                }
+            }
             if (array_key_exists('newTab', $item) && !is_bool($item['newTab'])) {
                 throw new InvalidMenu('In neuem Tab öffnen ist an oder aus.');
             }