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/Controller/SettingsController.php

@@ -4,8 +4,10 @@ namespace App\Controller;
 
 use App\Content\Consent;
 use App\Content\DemoContent;
+use App\Content\Languages;
 use App\Content\NotFoundPage;
 use App\Content\PageRepository;
+use App\Content\PostRepository;
 use App\Content\RedirectRepository;
 use App\Content\SiteSettings;
 use App\Content\SocialProfiles;
@@ -19,7 +21,7 @@ use Symfony\Component\Routing\Attribute\Route;
 
 final class SettingsController extends AbstractController
 {
-    public function __construct(private SiteSettings $settings, private RedirectRepository $redirects, private PageRepository $pages, private Theme $theme, private NotFoundPage $notFoundPage)
+    public function __construct(private SiteSettings $settings, private RedirectRepository $redirects, private PageRepository $pages, private Theme $theme, private NotFoundPage $notFoundPage, private Languages $languages, private PostRepository $posts)
     {
     }
 
@@ -67,9 +69,52 @@ final class SettingsController extends AbstractController
             'socialNetworks' => SocialProfiles::NETWORKS,
             'weekdays' => SiteSettings::DAYS,
             'socialPlaceholders' => SocialProfiles::PLACEHOLDERS,
+            'mainLanguage' => $this->languages->describe($this->languages->main()),
+            'extraLanguages' => $this->languages->extra(),
+            'terms' => [] === $this->languages->extra() ? [] : $this->posts->allTerms(),
+            'languageCatalog' => array_map(fn (string $code): array => $this->languages->describe($code), array_values(array_diff(array_keys(Languages::CATALOG), [$this->languages->main()]))),
         ]);
     }
 
+    /**
+     * Die weiteren Sprachen (ADR 111). Eine Sprache dazunehmen ändert an der Website nichts,
+     * solange keine Seite übersetzt und veröffentlicht ist; eine Sprache wegnehmen nimmt ihre
+     * Seiten vom Netz, lässt die Übersetzungen aber in den Seiten liegen.
+     */
+    /** Kategorien, Schlagwörter und Einwilligungshinweis in den weiteren Sprachen (ADR 111). */
+    #[Route('/%kant.admin_path%/settings/sprachen/texte', name: 'admin_language_texts_save', methods: ['POST'])]
+    public function saveLanguageTexts(Request $request): Response
+    {
+        $this->denyAccessUnlessGranted('ROLE_ADMIN');
+        if (!$this->isCsrfTokenValid('settings', $request->request->getString('_csrf_token'))) {
+            return $this->back('Deine Sitzung ist abgelaufen. Bitte melde dich erneut an.');
+        }
+        $all = $request->request->all();
+        $this->settings->saveLanguageTexts(is_array($all['termNames'] ?? null) ? $all['termNames'] : [], is_array($all['consentTexts'] ?? null) ? $all['consentTexts'] : []);
+        $this->addFlash('success', 'Die Übersetzungen wurden gespeichert.');
+
+        return $this->redirectToRoute('admin_settings', ['_fragment' => 'sprachen']);
+    }
+
+    #[Route('/%kant.admin_path%/settings/sprachen', name: 'admin_languages_save', methods: ['POST'])]
+    public function saveLanguages(Request $request): Response
+    {
+        $this->denyAccessUnlessGranted('ROLE_ADMIN');
+        if (!$this->isCsrfTokenValid('settings', $request->request->getString('_csrf_token'))) {
+            return $this->back('Deine Sitzung ist abgelaufen. Bitte melde dich erneut an.');
+        }
+        try {
+            $this->languages->save(array_values(array_map('strval', (array) ($request->request->all()['languages'] ?? []))));
+        } catch (InvalidPage $e) {
+            $this->addFlash('error', $e->getMessage());
+
+            return $this->redirectToRoute('admin_settings', ['_fragment' => 'sprachen']);
+        }
+        $this->addFlash('success', [] === $this->languages->extra() ? 'Die Website ist einsprachig.' : 'Die Sprachen wurden gespeichert. Übersetzt wird im Editor jeder Seite über den Sprachumschalter oben.');
+
+        return $this->redirectToRoute('admin_settings', ['_fragment' => 'sprachen']);
+    }
+
     #[Route('/%kant.admin_path%/settings/company', name: 'admin_settings_save', methods: ['POST'])]
     public function save(Request $request): Response
     {