Lehrplan: Country-Helper + Landeinstellung live

- App/php/lib/Country.php: Kaskade session → classes → teachers →
  cookie → 'AT', Helper current()/flag()/label()/allCountries()
- App/php/api/country.php: GET + POST /api/country
- country-Spalten in teachers, classes, student_sessions (idempotent)
- Native-<select>-Picker im Header aller öffentlichen Seiten
  (modul-*.php, lehrplan.php, simulationen.php)
- Footer-Links "Andere Länder: 🇨🇭 🇩🇪 🇱🇮"
- lehrplan.php liest Default-Filter jetzt aus Country::current()
- iPad-freundlich: Native Select gibt Wheel-Picker auf iOS,
  Touch-Ziel >=40px

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

App/pages/simulationen.php

@@ -13,6 +13,7 @@
 require_once __DIR__ . '/../php/config/app.php';
 require_once __DIR__ . '/../php/config/db.php';
 require_once __DIR__ . '/../php/lib/EasyLang.php';
+require_once __DIR__ . '/../php/lib/Country.php';
 
 $db = getDB();
 
@@ -270,6 +271,7 @@ $statusMeta = [
   <?php if ($easyActive): ?>
     <span class="sp-btn-sm sp-easy-pill">🟢 Leichte Sprache</span>
   <?php endif; ?>
+  <?php include __DIR__ . '/_partials/country_picker.php'; ?>
   <a href="<?= $bp ?>/pages/lehrplan.php" class="sp-btn-sm">Lehrplan</a>
   <a href="<?= $bp ?>/glossar" class="sp-btn-sm">Glossar</a>
   <a href="<?= $bp ?>/login.html" class="sp-btn-sm sp-btn-primary">Anmelden</a>
@@ -400,6 +402,7 @@ $statusMeta = [
     <a href="<?= $bp ?>/impressum.html">Impressum</a> ·
     <a href="<?= $bp ?>/datenschutz.html">Datenschutz</a>
   </div>
+  <?php include __DIR__ . '/_partials/country_footer.php'; ?>
 </footer>
 
 <script>