Implement authenticate/update message handling for Qwen OAuth authentication

- Added authenticate_update method to ACP schema constants
- Added AuthenticateUpdateNotification type definitions
- Updated ACP message handler to process authenticate/update notifications
- Added VS Code notification handler with 'Open in Browser' and 'Copy Link' options
- Integrated authenticate update handling in QwenAgentManager

This implementation allows users to easily authenticate with Qwen OAuth when automatic browser launch fails by providing a notification with direct link and copy functionality.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

packages/vscode-ide-companion/src/utils/authNotificationHandler.ts

@@ -0,0 +1,40 @@
+/**
+ * @license
+ * Copyright 2025 Qwen Team
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import * as vscode from 'vscode';
+import type { AuthenticateUpdateNotification } from '../types/acpTypes.js';
+
+/**
+ * Handle authentication update notifications by showing a VS Code notification
+ * with the authentication URI and a copy button.
+ *
+ * @param data - Authentication update notification data containing the auth URI
+ */
+export function handleAuthenticateUpdate(
+  data: AuthenticateUpdateNotification,
+): void {
+  const authUri = data._meta.authUri;
+
+  // Show an information message with the auth URI and copy button
+  vscode.window
+    .showInformationMessage(
+      `Qwen Code needs authentication. Click the button below to open the authentication page or copy the link to your browser.`,
+      'Open in Browser',
+      'Copy Link',
+    )
+    .then((selection) => {
+      if (selection === 'Open in Browser') {
+        // Open the authentication URI in the default browser
+        vscode.env.openExternal(vscode.Uri.parse(authUri));
+      } else if (selection === 'Copy Link') {
+        // Copy the authentication URI to clipboard
+        vscode.env.clipboard.writeText(authUri);
+        vscode.window.showInformationMessage(
+          'Authentication link copied to clipboard!',
+        );
+      }
+    });
+}