Send the model and CLI version with the user agent (#14865)

packages/core/src/utils/version.ts

@@ -0,0 +1,17 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { getPackageJson } from './package.js';
+import { fileURLToPath } from 'node:url';
+import path from 'node:path';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
+export async function getVersion(): Promise<string> {
+  const pkgJson = await getPackageJson(__dirname);
+  return process.env['CLI_VERSION'] || pkgJson?.version || 'unknown';
+}