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>

templates/blocks/post-list.html.twig

@@ -14,7 +14,7 @@
                  srcset="{% for source in post.image.variants %}{{ source.src }} {{ source.width }}w{% if not loop.last %}, {% endif %}{% endfor %}" sizes="(max-width: 650px) 100vw, 380px">
             {# Der Hinweis liegt über dem Bild und erscheint beim Zeigen. Für Vorlesesoftware ist
                er nichts Neues - der Titel darunter ist derselbe Verweis -, deshalb ausgeblendet. #}
-            <span class="post-view" aria-hidden="true">Ansehen</span>
+            <span class="post-view" aria-hidden="true">{{ 'Ansehen'|kant_t }}</span>
         </a>
         {% endif %}
         <div class="post-body">
@@ -22,14 +22,14 @@
             {% if (showMeta ?? true) and (post.publishedAt or post.author) %}
             <p class="post-meta">
                 {% if post.publishedAt %}<time datetime="{{ post.publishedAt|date('Y-m-d') }}">{{ post.publishedAt|date('d.m.Y') }}</time>{% endif %}
-                {% if post.author %}<span>von {{ post.author }}</span>{% endif %}
+                {% if post.author %}<span>{{ 'von'|kant_t }} {{ post.author }}</span>{% endif %}
             </p>
             {% endif %}
             {% if (showExcerpt ?? true) and post.excerpt %}<p class="post-excerpt">{{ post.excerpt }}</p>{% endif %}
             {# Ein Element, das aussieht wie ein Knopf, muss eines sein. Vorher stand hier eine
                reine Beschriftung: sichtbar, aber nicht anklickbar. Der Titel steckt für
                Vorlesesoftware mit drin, damit "Weiterlesen" nicht zwölfmal gleich heißt. #}
-            {% if art == 'wechsel' %}<a class="post-more" href="{{ post.href }}">Weiterlesen<span class="visually-hidden">: {{ post.title }}</span></a>{% endif %}
+            {% if art == 'wechsel' %}<a class="post-more" href="{{ post.href }}">{{ 'Weiterlesen'|kant_t }}<span class="visually-hidden">: {{ post.title }}</span></a>{% endif %}
             {% if (showTerms ?? true) and post.terms.category is not empty %}
             <p class="post-terms">{% for term in post.terms.category %}<a href="{{ term.href }}">{{ term.name }}</a>{% endfor %}</p>
             {% endif %}
@@ -40,9 +40,9 @@
 {% endif %}
 {% if pages|default(1) > 1 %}
 {# Dieselbe Blätterleiste wie im Archiv: eine Liste, die mehr hat als sie zeigt, sagt es. #}
-<nav class="post-pager" aria-label="Weitere Beiträge">
-    {% if page > 1 %}<a rel="prev" href="?seite={{ page - 1 }}">← Neuere</a>{% endif %}
-    <span>Seite {{ page }} von {{ pages }}{% if total %} · {{ total }} Beiträge{% endif %}</span>
-    {% if page < pages %}<a rel="next" href="?seite={{ page + 1 }}">Ältere →</a>{% endif %}
+<nav class="post-pager" aria-label="{{ 'Weitere Beiträge'|kant_t }}">
+    {% if page > 1 %}<a rel="prev" href="?seite={{ page - 1 }}">{{ '← Neuere'|kant_t }}</a>{% endif %}
+    <span>{{ 'Seite %d von %d'|kant_t|format(page, pages) }}{% if total %} · {{ total }} {{ 'Beiträge'|kant_t }}{% endif %}</span>
+    {% if page < pages %}<a rel="next" href="?seite={{ page + 1 }}">{{ 'Ältere →'|kant_t }}</a>{% endif %}
 </nav>
 {% endif %}