Add missing license file for whoami_sync_worker_router.js.j2

roles/custom/matrix-synapse-reverse-proxy-companion/templates/nginx/njs/whoami_sync_worker_router.js.j2.license

@@ -0,0 +1,3 @@
+SPDX-FileCopyrightText: 2026 Slavi Pantaleev
+
+SPDX-License-Identifier: AGPL-3.0-or-later