feat: Add User-Agent to API requests

This change introduces a User-Agent header to all API requests made by the Gemini CLI.

The User-Agent string includes the CLI version, Node.js version, operating system, and architecture. This will help in tracking usage and identifying potential issues.

Fixes https://b.corp.google.com/issues/416353675

Signed-off-by: Gemini

packages/server/src/core/client.ts

@@ -34,7 +34,15 @@ export class GeminiClient {
   private readonly MAX_TURNS = 100;
 
   constructor(private config: Config) {
-    this.client = new GoogleGenAI({ apiKey: config.getApiKey() });
+    const userAgent = config.getUserAgent();
+    this.client = new GoogleGenAI({
+      apiKey: config.getApiKey(),
+      httpOptions: {
+        headers: {
+          'User-Agent': userAgent,
+        },
+      },
+    });
     this.model = config.getModel();
   }