fix: filter channel team task events from web UI chat

Admin users were seeing team task notifications from other channels
(Discord, Telegram, Lark) in their web UI chat due to bypassing the
UserID event filter. Added channel check to handleTeamTaskEvent matching
the existing pattern in handleAgentEvent.

ui/web/src/pages/chat/hooks/use-chat-messages.ts

@@ -437,9 +437,16 @@ export function useChatMessages(sessionKey: string, agentId: string) {
         progress_percent?: number;
         progress_step?: string;
         reason?: string;
+        channel?: string;
       };
       if (!event?.team_id) return;
 
+      // Only process team task events from WS channel (matches handleAgentEvent filter).
+      // Prevents channel events (Telegram, Discord, etc.) leaking into web UI chat.
+      if (event.channel && event.channel !== "ws") {
+        return;
+      }
+
       setTeamTasks((prev) => {
         const existing = prev.find((t) => t.taskId === event.task_id);