This pull request introduces improvements to the shutdown logic of the daemon, allowing for a "soft exit" mode that gracefully shuts down non-Docker instances while skipping Docker instances. This enhances the shutdown process by providing a safer, less disruptive way to stop services unless a forceful shutdown is required. Additionally, there are minor code style and import order adjustments.

Shutdown logic improvements:

• Added a new softExit method to InstanceSubsystem that skips Docker instances and attempts a soft shutdown of general instances. If instances take too long to stop, they are forcefully closed after a timeout.
• Updated the shutdown signal handlers in app.ts to use the new soft exit logic by default when receiving process signals or the "exit" command, only performing a forceful exit if necessary. [1] [2]

Minor code improvements:

• Fixed a missing semicolon and improved import order in app.ts for consistency. [1] [2]

已知问题：在某些 Linux 环境下，直接在前台按 Ctrl+C 无法正常触发对非 Docker 实例的软关闭（可能与终端、systemd 或容器化运行时的信号传播有关，systemd更改KillMode=process可正常运关闭）。