fix(test): resolve CI timing race in TestFakeCmdInfra

问题：TestFakeCmdInfra/integration_with_runCodexTask 在 CI 环境中间歇性失败
原因：WaitDelay(1ms) 与 stdout 事件延迟(1ms) 过于接近，在 CI 负载下
     Wait() 可能在第二个 JSON 事件写入前返回，导致过早关闭 stdout

修复：将 WaitDelay 从 1ms 增加到 5ms，确保 Wait() 在所有 stdout
     数据写入后才返回，消除竞态条件

测试：本地和 -race 模式均通过

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

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

codex-wrapper/main_test.go

@@ -618,7 +618,7 @@ func TestFakeCmdInfra(t *testing.T) {
 					Data:  `{"type":"item.completed","item":{"type":"agent_message","text":"fake-msg"}}` + "\n",
 				},
 			},
-			WaitDelay: time.Millisecond,
+				WaitDelay: 5 * time.Millisecond,
 		})
 
 		newCommandRunner = func(ctx context.Context, name string, args ...string) commandRunner {