chore(dev): 按端口杀进程树，避免 Windows 孤儿监听

新增 stop.bat/ps1/sh，并写入本地开发规则：停服务用脚本、停后复核端口。

Co-authored-by: Cursor <cursoragent@cursor.com>

start.bat

@@ -57,7 +57,8 @@ echo   Backend:   http://localhost:3001
 echo   Data dir:  %~dp0backend\data
 echo   Database:  localhost:5432
 echo.
-echo   Close each window to stop the service.
+echo   Prefer stop:  stop.bat  (kills :3000/:3001 process trees)
+echo   Or close each service window.
 echo   Stop database: docker compose down
 echo ============================================
 pause