Flow 0.4.11 · Responsive background exit and compact toolbar

修复后台退出迟缓：托盘退出直接通知引擎停止，不再等待接口请求队列，并主动关闭隐藏窗口。保留任务保存与正常清理流程，新增停止信号、重复停止、重试和快速释放目录锁测试。工具栏改为紧凑矢量图标与中英文悬停说明；Tracker 订阅设置无需选中任务即可打开；子窗口移除收起按钮。独立安装器与小型卸载器保留。

Fixes slow background exit: the tray requests engine shutdown directly, bypassing pending API requests, and actively closes the hidden window. Task saving and normal cleanup are retained. Adds tests for stop signals, repeated shutdown, retry safety and prompt directory-lock release. Compact vector toolbar icons have localized hover hints. Tracker subscriptions are available without a selected task; utility windows no longer collapse. Independent installer and small uninstaller remain included.

Validation: 57 tests passed across the app, installer and uninstaller; 2 optional player tests ignored. Packaged backend self-check, signed update manifest and asset SHA-256 verified.

Downloads: Flow-Setup-0.4.11-x64.exe is the installer; Flow-0.4.11-windows-x64-portable.zip is the portable package. Exit Flow completely before installing.