[license] client/simple: SPDX-License-Identifier: AGPL-3.0-or-later

SPDX short-form identifiers to communicate license information in a simple,
efficient, portable and machine-readable manner [1]

[1] https://spdx.dev/learn/handling-license-info/

client/simple/src/js/main/infinite_scroll.ts

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 import { assertElement, http, settings } from "../core/toolkit.ts";
 
 const newLoadSpinner = (): HTMLDivElement => {