feat: 实现定时任务系统

- 新增 platform_scheduled_tasks, platform_task_logs, platform_script_vars, platform_secrets 数据库表
- 实现 ScriptSDK 提供 AI/通知/DB/HTTP/变量存储/参数获取等功能
- 实现安全的脚本执行器，支持沙箱环境和禁止危险操作
- 实现 APScheduler 调度服务，支持简单时间点和 CRON 表达式
- 新增定时任务 API 路由，包含 CRUD、执行、日志、密钥管理
- 新增定时任务前端页面，支持脚本编辑、测试运行、日志查看

backend/app/main.py

@@ -14,12 +14,10 @@ from .routers.wechat import router as wechat_router
 from .routers.alerts import router as alerts_router
 from .routers.cost import router as cost_router
 from .routers.quota import router as quota_router
-from .routers.tool_configs import router as tool_configs_router
 from .routers.tasks import router as tasks_router
-from .routers.scripts import router as scripts_router
 from .middleware import TraceMiddleware, setup_exception_handlers, RequestLoggerMiddleware
 from .middleware.trace import setup_logging
-from .services.scheduler import start_scheduler, shutdown_scheduler
+from .services.scheduler import scheduler_service
 
 # 配置日志（包含 TraceID）
 setup_logging(level=logging.INFO, include_trace=True)
@@ -70,29 +68,20 @@ app.include_router(wechat_router, prefix="/api")
 app.include_router(alerts_router, prefix="/api")
 app.include_router(cost_router, prefix="/api")
 app.include_router(quota_router, prefix="/api")
-app.include_router(tool_configs_router, prefix="/api")
-app.include_router(tasks_router, prefix="/api")
-app.include_router(scripts_router, prefix="/api")
+app.include_router(tasks_router)
 
 
+# 应用生命周期事件
 @app.on_event("startup")
 async def startup_event():
-    """应用启动时初始化调度器"""
-    try:
-        start_scheduler()
-        logging.info("Scheduler started successfully")
-    except Exception as e:
-        logging.error(f"Failed to start scheduler: {e}")
+    """应用启动时启动调度器"""
+    scheduler_service.start()
 
 
 @app.on_event("shutdown")
 async def shutdown_event():
-    """应用关闭时停止调度器"""
-    try:
-        shutdown_scheduler()
-        logging.info("Scheduler shutdown successfully")
-    except Exception as e:
-        logging.error(f"Failed to shutdown scheduler: {e}")
+    """应用关闭时关闭调度器"""
+    scheduler_service.shutdown()
 
 
 @app.get("/")