fix(ai_trade): post-close trigger를 상태기반으로 변경 (F3)

코드 리뷰 F3: _is_post_close_trigger가 16:00:00-16:00:59 1분 윈도우만 true.
5분 sleep + 비결정적 cycle 시작시각 조합으로 영영 못 잡는 경우 존재
(예: cycle이 15:31에 시작하면 15:36, 15:41 ... 16:01에 깸).

"오늘 아직 post-close 안 돌렸고 현재 시각 ≥ 16:00" 상태기반으로 변경.
poll_loop가 last_post_close_date 변수로 일 1회 실행 보장.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ai_trade/tests/test_pull_worker.py

@@ -129,3 +129,51 @@ def test_poll_loop_calls_generate_signals_after_cycle(monkeypatch):
     assert state.signals["005930"]["action"] == "sell"
     assert state.signals["005930"]["confidence_webai"] == 1.0
     dedup.record.assert_called_with("005930", "sell", confidence=1.0)
+
+
+async def test_post_close_fires_at_1601_when_not_yet_today(monkeypatch):
+    """F3 — 16:01에 깬 cycle도 오늘 post_close 안 돌렸으면 호출됨 (회귀 방지)."""
+    from datetime import datetime as _dt
+    from zoneinfo import ZoneInfo as _ZI
+    import asyncio as _asyncio
+
+    from ai_trade import pull_worker
+
+    _kst = _ZI("Asia/Seoul")
+    now_at_1601 = _dt(2026, 5, 18, 16, 1, tzinfo=_kst)
+
+    class FrozenDateTime:
+        @staticmethod
+        def now(tz=None):
+            return now_at_1601
+
+    monkeypatch.setattr(pull_worker, "datetime", FrozenDateTime)
+    monkeypatch.setattr(pull_worker, "_is_market_day", lambda n: True)
+    monkeypatch.setattr(pull_worker, "_is_polling_window", lambda n: True)
+    monkeypatch.setattr(pull_worker, "_next_interval", lambda n: 0.01)
+    monkeypatch.setattr(pull_worker, "_run_polling_cycle", AsyncMock())
+    monkeypatch.setattr(pull_worker, "update_minute_momentum_for_all", lambda s: None)
+    post_close = AsyncMock()
+    monkeypatch.setattr(pull_worker, "_run_post_close_cycle", post_close)
+
+    state = MagicMock()
+    chronos = MagicMock()
+    kis = MagicMock()
+    shutdown = _asyncio.Event()
+
+    async def _stop_soon():
+        await _asyncio.sleep(0.05)
+        shutdown.set()
+
+    _asyncio.create_task(_stop_soon())
+    await pull_worker.poll_loop(
+        client=MagicMock(),
+        state=state,
+        shutdown=shutdown,
+        kis_client=kis,
+        chronos=chronos,
+        dedup=None,
+        settings=None,
+    )
+
+    assert post_close.await_count >= 1, "post-close가 16:01에 호출되지 않음 (F3 회귀)"