feat: add 8 builtin tools, AgentSchedules management page, Celery Beat integration

- Add 3 schedule tools (create/list/delete) and 5 utility tools (crypto, random, email, URL, regex)
- Add frontend AgentSchedules.vue page with full CRUD, cron presets, manual trigger
- Integrate Celery Beat for automatic schedule execution
- Update startup scripts with Celery Beat launch
- Fix schedule list API to show all schedules for admin users
- Add celrybeat-schedule.* to .gitignore

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -27,6 +27,9 @@ tessdata/
 __pycache__/
 *.py[cod]
 
+# Celery Beat 运行时文件
+celerybeat-schedule.*
+
 # 本机运行产物 / 大文件（勿提交）
 agent_workspaces/
 uploads/