fix(cli): Prevent stdout/stderr patching for extension commands (#13600)

Co-authored-by: jacob314 <jacob314@gmail.com>

packages/cli/src/commands/mcp/add.ts

@@ -8,6 +8,7 @@
 import type { CommandModule } from 'yargs';
 import { loadSettings, SettingScope } from '../../config/settings.js';
 import { debugLogger, type MCPServerConfig } from '@google/gemini-cli-core';
+import { exitCli } from '../utils.js';
 
 async function addMcpServer(
   name: string,
@@ -230,5 +231,6 @@ export const addCommand: CommandModule = {
         excludeTools: argv['excludeTools'] as string[] | undefined,
       },
     );
+    await exitCli();
   },
 };