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/lehrplan.php

@@ -15,14 +15,19 @@
 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();
 
-// Filter aus URL (sanft, nur Whitelist-Werte)
+// Filter: Default ist das aktuelle Landes-Setting (Kaskade), per URL überschreibbar
 $allowedCountries = ['AT', 'DE', 'CH', 'LI'];
-$qCountry = strtoupper(trim($_GET['country'] ?? 'AT'));
-if (!in_array($qCountry, $allowedCountries, true) && $qCountry !== 'ALL') {
-    $qCountry = 'AT';   // Default
+if (isset($_GET['country'])) {
+    $qCountry = strtoupper(trim($_GET['country']));
+    if (!in_array($qCountry, $allowedCountries, true) && $qCountry !== 'ALL') {
+        $qCountry = Country::current();
+    }
+} else {
+    $qCountry = Country::current();
 }
 
 $qTheme  = preg_replace('/[^a-z0-9_-]/', '', strtolower($_GET['theme'] ?? ''));
@@ -359,6 +364,7 @@ $categoryMeta = [
   <?php if ($easyActive): ?>
     <span class="lp-btn-sm lp-easy-pill">🟢 Leichte Sprache</span>
   <?php endif; ?>
+  <?php include __DIR__ . '/_partials/country_picker.php'; ?>
   <a href="<?= $bp ?>/pages/simulationen.php" class="lp-btn-sm">Simulationen</a>
   <a href="<?= $bp ?>/glossar" class="lp-btn-sm">Glossar</a>
   <a href="<?= $bp ?>/login.html" class="lp-btn-sm lp-btn-primary">Anmelden</a>
@@ -557,6 +563,7 @@ $categoryMeta = [
     <a href="<?= $bp ?>/impressum.html">Impressum</a> ·
     <a href="<?= $bp ?>/datenschutz.html">Datenschutz</a>
   </div>
+  <?php include __DIR__ . '/_partials/country_footer.php'; ?>
 </footer>
 
 <script>