fix: 修复定时任务模型字段与数据库表不匹配的问题

- task_type -> execution_type
- status -> is_enabled
- 移除不存在的字段 webhook_method, webhook_headers, script_timeout
- time_points/input_params 适配 JSON 类型

backend/app/services/scheduler.py

@@ -49,7 +49,7 @@ class SchedulerService:
         """从数据库加载所有启用的任务"""
         db = SessionLocal()
         try:
-            tasks = db.query(ScheduledTask).filter(ScheduledTask.status == 1).all()
+            tasks = db.query(ScheduledTask).filter(ScheduledTask.is_enabled == True).all()
             for task in tasks:
                 self._add_task_to_scheduler(task)
             print(f"已加载 {len(tasks)} 个定时任务")
@@ -81,7 +81,7 @@ class SchedulerService:
         elif task.schedule_type == 'simple' and task.time_points:
             # 简单模式 - 多个时间点
             try:
-                time_points = json.loads(task.time_points)
+                time_points = task.time_points if isinstance(task.time_points, list) else json.loads(task.time_points)
                 for i, time_point in enumerate(time_points):
                     hour, minute = map(int, time_point.split(':'))
                     sub_job_id = f"{job_id}_{i}"
@@ -100,7 +100,7 @@ class SchedulerService:
         db = SessionLocal()
         try:
             task = db.query(ScheduledTask).filter(ScheduledTask.id == task_id).first()
-            if task and task.status == 1:
+            if task and task.is_enabled:
                 self._add_task_to_scheduler(task)
         finally:
             db.close()
@@ -172,12 +172,9 @@ class SchedulerService:
             # 解析输入参数
             params = {}
             if task.input_params:
-                try:
-                    params = json.loads(task.input_params)
-                except:
-                    pass
+                params = task.input_params if isinstance(task.input_params, dict) else {}
             
-            if task.task_type == 'webhook':
+            if task.execution_type == 'webhook':
                 success, output, error = await self._execute_webhook(task)
             else:
                 success, output, error = await self._execute_script(db, task, trace_id, params)
@@ -206,20 +203,12 @@ class SchedulerService:
     async def _execute_webhook(self, task: ScheduledTask):
         """执行Webhook任务"""
         try:
-            headers = {}
-            if task.webhook_headers:
-                headers = json.loads(task.webhook_headers)
-            
             body = {}
             if task.input_params:
-                body = json.loads(task.input_params)
+                body = task.input_params if isinstance(task.input_params, dict) else {}
             
             async with httpx.AsyncClient(timeout=30) as client:
-                if task.webhook_method.upper() == 'GET':
-                    response = await client.get(task.webhook_url, headers=headers, params=body)
-                else:
-                    response = await client.post(task.webhook_url, headers=headers, json=body)
-                
+                response = await client.post(task.webhook_url, json=body)
                 response.raise_for_status()
                 return True, response.text[:5000], ''
                 
@@ -238,7 +227,7 @@ class SchedulerService:
             tenant_id=task.tenant_id,
             trace_id=trace_id,
             params=params,
-            timeout=task.script_timeout or 300
+            timeout=300  # 默认超时
         )
         
         return success, output, error
@@ -285,14 +274,6 @@ class SchedulerService:
             if not task:
                 return {"success": False, "error": "任务不存在"}
             
-            # 解析参数
-            params = {}
-            if task.input_params:
-                try:
-                    params = json.loads(task.input_params)
-                except:
-                    pass
-            
             success, output, error = await self._execute_task_once(db, task)
             
             return {