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>

backend/app/api/agent_schedules.py

@@ -72,12 +72,10 @@ async def list_schedules(
     db: Session = Depends(get_db),
 ):
     """获取当前用户的所有定时任务。"""
-    schedules = (
-        db.query(AgentSchedule)
-        .filter(AgentSchedule.user_id == current_user.id)
-        .order_by(AgentSchedule.created_at.desc())
-        .all()
-    )
+    query = db.query(AgentSchedule)
+    if current_user.role != "admin":
+        query = query.filter(AgentSchedule.user_id == current_user.id)
+    schedules = query.order_by(AgentSchedule.created_at.desc()).all()
     return schedules