修复: run_command 空路径报错 + 隧道日志洪水 + 启动残留清理

- tool_registry: run_command working_dir 空字符串 "" → None，修 Windows os error 123
- lib: tunnel subscriber 从频率压制(suppress_until)改为连接状态感知(is_connected)，
  断开时静默丢弃事件，重连后恢复透传，记 INFO 状态变迁(治本)
- conversation_repo: 新增 cleanup_stale_pending()，超 24h 残留 pending 标记 interrupted
- restore: 启动时先清理过期 pending 再恢复审批
- state: 实现 cleanup_orphan_pending_messages()，启动时清理对应已决/超时 tool 的
  __PENDING__ 占位消息

crates/df-storage/src/crud/conversation_repo.rs

@@ -264,6 +264,25 @@ impl AiToolExecutionRepo {
         .map_err(storage_err)?
     }
 
+    /// 清理超期的残留 pending 工具调用(旧会话遗留)。
+    ///
+    /// `max_age_secs`: 超过此秒数的 pending 记录被标记为 interrupted(不硬删,保留审计痕迹)。
+    pub async fn cleanup_stale_pending(&self, max_age_secs: u64) -> Result<u64> {
+        let conn = self.conn.clone();
+        let cutoff_ms = (df_types::now_millis() as i64 - (max_age_secs as i64 * 1000)).to_string();
+        let affected = tokio::task::spawn_blocking(move || {
+            let guard = conn.blocking_lock();
+            guard.execute(
+                "UPDATE ai_tool_executions SET status = 'interrupted' \
+                 WHERE status = 'pending' AND CAST(requested_at AS INTEGER) < ?1",
+                params![cutoff_ms],
+            ).map_err(storage_err)
+        })
+        .await
+        .map_err(storage_err)??;
+        Ok(affected as u64)
+    }
+
     /// 审批历史面板分页查询:按 requested_at 倒序(最新在前),limit 默认 50。
     ///
     /// 与 list_pending 同理走专用 SELECT,绕过通用 query 宏(后者硬编码