feat: Add API key authentication (#1254)

Closes #945

server/api/policies/is-session.js

@@ -0,0 +1,12 @@
+/*!
+ * Copyright (c) 2024 PLANKA Software GmbH
+ * Licensed under the Fair Use License: https://github.com/plankanban/planka/blob/master/LICENSE.md
+ */
+
+module.exports = async function isSession(req, res, proceed) {
+  if (!req.currentSession) {
+    return res.notFound(); // Forbidden
+  }
+
+  return proceed();
+};