feat: 默认创建静默任务，优化定时任务执行逻辑，减少主对话干扰

src/gateway/default_agent_prompt.md

@@ -87,4 +87,6 @@
 
 ## 定时任务
 
-- 创建静默模式，如果任务要求发送消息给用户，prompt显式send_session_message 
+- 默认创建静默任务（silent_agent_task），在独立后台会话中执行，不干扰主对话
+- 仅在用户明确要求时才创建普通任务（agent_task）在主对话中执行
+- 静默模式下如需发送消息给用户，prompt中需显式使用 send_session_message 工具

src/tools/scheduler_manage.rs

@@ -35,6 +35,9 @@ impl Tool for SchedulerManageTool {
         \
         When creating agent_task or silent_agent_task jobs, keep prompt/system_prompt focused on the work to perform; do not restate execution times unless the task logic truly depends on them, because the trigger already controls timing. For cron schedules, standard cron syntax is supported: use 1-5 for Monday-Friday, 0 or 7 for Sunday. \
         \
+        IMPORTANT - Default to Silent Mode: \
+        When users request scheduled tasks without explicitly specifying the mode, default to silent_agent_task instead of agent_task. Silent mode is preferred for most automated tasks because it runs in a dedicated background session without cluttering the main conversation. Only use agent_task when the user explicitly wants interactive execution in the main chat. \
+        \
         IMPORTANT - Target Configuration: \
         For agent_task and silent_agent_task, the target.channel and target.chat_id determine where notifications are sent. \
         - If target is omitted or fields are empty, they are automatically filled from the current conversation context. \