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>

scripts/editor-check.mjs

@@ -1147,9 +1147,8 @@ try {
   assert.equal(await savedOg.inputValue(), chosenOg, 'the image survives saving');
   checks.push({ name: 'image fields in the content settings pick from the library', passed: true });
   // Formular-Editor: Bedingung, Antwortadresse und Bild je Option werden gewählt, nicht getippt.
-  await page.goto(origin + '/admin/forms');
+  await page.goto(origin + '/admin/forms/neu');
   const neu = page.locator('#neues-formular');
-  if (!(await neu.evaluate(details => details.open))) await neu.locator('summary').click();
   await neu.locator('[name="name"]').fill('Anfrage Prüfung');
   await neu.locator('[name="slug"]').fill('anfrage-pruefung');
   await neu.locator('[name="recipient"]').fill('info@example.com');