feat: require an api key to schedule

web/api/db.php

@@ -61,3 +61,16 @@ function error_out(string $message, int $status = 400): never
 {
     json_out(['error' => $message], $status);
 }
+
+/**
+ * Aborts with 400 if no Clickatell API key has been configured.
+ */
+function require_api_key(): void
+{
+    $stmt = db()->prepare("SELECT setting_value FROM `system` WHERE setting_name = 'clickatell_api_key'");
+    $stmt->execute();
+    $key = $stmt->fetchColumn();
+    if ($key === false || trim((string) $key) === '') {
+        error_out('No Clickatell API key is configured. Set one in Admin → Clickatell Settings before sending or scheduling messages.', 400);
+    }
+}