Fix: Error 500 on health.php and export button missing.

src/lib/admin.php

@@ -3,7 +3,9 @@
 require_once __DIR__ . '/common.php';
 
 function gridtv_require_admin(array $config, string $page_title = 'Admin'): array {
-    session_start();
+    if (session_status() !== PHP_SESSION_ACTIVE) {
+        session_start();
+    }
 
     $admin_key = (string) ($config['admin_key'] ?? '');
     $session_key = $_SESSION['gridtv_admin_unlocked'] ?? '';

src/tpl/topbar.php

@@ -12,6 +12,7 @@
 <?php if (!empty($m3u_url)): ?>
     <button class="copy-btn" onclick="copyUrl('m3u')" title="<?= htmlspecialchars($L["copy_m3u"]) ?>"><?= htmlspecialchars($L["copy_m3u"]) ?></button>
 <?php endif; ?>
+    <a class="copy-btn" href="/export.php" title="Export 24h">PDF</a>
   </div>
 <?php if (count($epg_sources) > 1 || $allow_personal_epg): ?>
   <div class="source-dropdown" id="sourceDropdown">