Add apache2 SPDX headers to all source files (#48)

packages/cli/src/config/config.ts

@@ -1,3 +1,9 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
 import yargs from 'yargs/yargs';
 import { hideBin } from 'yargs/helpers';
 import * as dotenv from 'dotenv';