Document title follows the configured instance name (#323)

useDocumentTitle pinned APP_NAME = 'Dorfteich', so every route title —
tab, bookmarks, the window title a screen reader announces (WCAG 2.4.2)
— named the product instead of the operator's instance. The trailing
name now comes from the public branding query, exactly like the TopBar
brand (#306); until the query resolves (or when it cannot, e.g.
maintenance mode) the shipped default keeps the title stable, so an
untouched instance reads exactly as before. The static index.html title
stays the pre-JS placeholder — server-rendering it is #179's territory,
deliberately out of scope (recorded in the issue).

The admin-settings e2e now also asserts the title carries the new name
right after saving, without a reload.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017aviRTgWCcAHUh1SBoxf6P

apps/web/e2e/vs-nfd-marking.spec.ts

@@ -34,7 +34,7 @@ test('mode marked: card, checkbox marking, and point-of-choice marking', async (
   // select value — compliant choice clears it, violating choice brings it
   // back, no save in between.
   const regField = page.locator('label.field', {
-    has: page.locator('select[name="registrationMode"]'),
+    has: page.locator('select[name="auth.registrationMode"]'),
   });
   const regSelect = regField.locator('select');
   await regSelect.selectOption('open');
@@ -72,7 +72,7 @@ test('mode hidden: rows disappear, notes mark the hiding, a11y clean', async ({
 
   // Value-listed control: the compliant registration mode keeps only its
   // compliant choice (seed leaves it open = violating? then all options).
-  const regSelect = page.locator('select[name="registrationMode"]');
+  const regSelect = page.locator('select[name="auth.registrationMode"]');
   const regField = page.locator('label.field', { has: regSelect });
   const optionCount = await regSelect.locator('option').count();
   const marked = await regField.locator('.vs-nfd-mark').count();