fix(chat): 定时功能审计修复 — 消除重复解析 + ID碰撞 + 输入补全

审计发现修复：
- H-01: 存储 ParsedSchedule 避免重复 parse_nl_schedule 调用
- H-03: trigger ID 追加 UUID 片段防止高并发碰撞
- C-02: execute_trigger 验证错误信息明确系统 Hand 必须注册
- M-02: SchedulerService 传递 trigger_name 作为 task_description
- M-01: 添加拦截路径跳过 post_hook 的设计注释

crates/zclaw-kernel/src/scheduler.rs

@@ -77,7 +77,7 @@ impl SchedulerService {
         kernel_lock: &Arc<Mutex<Option<Kernel>>>,
     ) -> Result<()> {
         // Collect due triggers under lock
-        let to_execute: Vec<(String, String, String)> = {
+        let to_execute: Vec<(String, String, String, String)> = {
             let kernel_guard = kernel_lock.lock().await;
             let kernel = match kernel_guard.as_ref() {
                 Some(k) => k,
@@ -103,7 +103,8 @@ impl SchedulerService {
                 .filter_map(|t| {
                     if let zclaw_hands::TriggerType::Schedule { ref cron } = t.config.trigger_type {
                         if Self::should_fire_cron(cron, &now) {
-                            Some((t.config.id.clone(), t.config.hand_id.clone(), cron.clone()))
+                            // (trigger_id, hand_id, cron_expr, trigger_name)
+                            Some((t.config.id.clone(), t.config.hand_id.clone(), cron.clone(), t.config.name.clone()))
                         } else {
                             None
                         }
@@ -123,7 +124,7 @@ impl SchedulerService {
         // If parallel execution is needed, spawn each execute_hand in a separate task
         // and collect results via JoinSet.
         let now = chrono::Utc::now();
-        for (trigger_id, hand_id, cron_expr) in to_execute {
+        for (trigger_id, hand_id, cron_expr, trigger_name) in to_execute {
             tracing::info!(
                 "[Scheduler] Firing scheduled trigger '{}' → hand '{}' (cron: {})",
                 trigger_id, hand_id, cron_expr
@@ -138,6 +139,7 @@ impl SchedulerService {
                 let input = serde_json::json!({
                     "trigger_id": trigger_id,
                     "trigger_type": "schedule",
+                    "task_description": trigger_name,
                     "cron": cron_expr,
                     "fired_at": now.to_rfc3339(),
                 });

crates/zclaw-kernel/src/trigger_manager.rs

@@ -305,9 +305,10 @@ impl TriggerManager {
         };
 
         // Get hand (outside of our lock to avoid potential deadlock with hand_registry)
+        // System hands (prefixed with '_') must be registered at boot — same rule as create_trigger.
         let hand = self.hand_registry.get(&hand_id).await
             .ok_or_else(|| zclaw_types::ZclawError::InvalidInput(
-                format!("Hand '{}' not found", hand_id)
+                format!("Hand '{}' not found (system hands must be registered at boot)", hand_id)
             ))?;
 
         // Update state before execution