feat(security): implement IP verification and encryption for sensitive tokens

includes/cache.php

@@ -137,3 +137,24 @@ function fociz_cache_delete_pattern(string $prefix): bool {
         return false;
     }
 }
+
+/**
+ * Verwijdert alle verlopen items actief uit de cache tabel (AVG/GDPR opschoning)
+ */
+function fociz_cache_cleanup_expired(?PDO $db = null): int {
+    try {
+        $pdo = $db ?: get_db_connection();
+        ensure_app_cache_table($pdo);
+        $stmt = $pdo->prepare("DELETE FROM app_cache WHERE expires_at < ?");
+        $stmt->execute([time()]);
+        return $stmt->rowCount();
+    } catch (Throwable $e) {
+        error_log("fociz_cache_cleanup_expired error: " . $e->getMessage());
+        return 0;
+    }
+}
+
+// Probabilistische automatische GC (5% kans bij elke script execution)
+if (mt_rand(1, 20) === 1) {
+    fociz_cache_cleanup_expired();
+}