feat(agent-office): notification broadcast + telegram tracking + activity feed API

- Add WebSocket notification messages for task_assigned/task_completed
- Structure telegram send_message return value with ok/message_id
- Track telegram delivery status in task result_data
- Add test_telegram command to stock agent
- Add GET /api/agent-office/activity unified feed endpoint

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

agent-office/app/agents/stock.py

@@ -22,15 +22,24 @@ class StockAgent(BaseAgent):
 
             summary = self._format_news_summary(news, indices)
 
-            update_task_status(task_id, "succeeded", {
-                "summary": summary,
-                "news_count": len(news) if isinstance(news, list) else 0,
-            })
-
             await self.transition("reporting", "뉴스 요약 전송 중...")
 
             from ..telegram_bot import send_stock_summary
-            await send_stock_summary(summary)
+            tg_result = await send_stock_summary(summary)
+
+            update_task_status(task_id, "succeeded", {
+                "summary": summary,
+                "news_count": len(news) if isinstance(news, list) else 0,
+                "telegram_sent": tg_result.get("ok", False),
+                "telegram_message_id": tg_result.get("message_id"),
+            })
+
+            if not tg_result.get("ok"):
+                add_log(self.agent_id, "Telegram send failed", "warning", task_id)
+                if self._ws_manager:
+                    await self._ws_manager.send_notification(
+                        self.agent_id, "telegram_failed", task_id, "텔레그램 전송 실패"
+                    )
 
             await self.transition("idle", "뉴스 요약 완료")
 
@@ -40,6 +49,15 @@ class StockAgent(BaseAgent):
             await self.transition("idle", f"오류: {e}")
 
     async def on_command(self, command: str, params: dict) -> dict:
+        if command == "test_telegram":
+            from ..telegram_bot import send_message
+            result = await send_message("🔔 [주식 에이전트] 텔레그램 테스트 메시지입니다.")
+            return {
+                "ok": result.get("ok", False),
+                "message": "텔레그램 전송 성공" if result.get("ok") else "텔레그램 전송 실패",
+                "telegram_message_id": result.get("message_id"),
+            }
+
         if command == "fetch_news":
             await self.on_schedule()
             return {"ok": True, "message": "뉴스 수집 시작"}