feat(signal_v2-phase3b): post-close cycle + minute momentum update

scheduler._is_post_close_trigger: 16:00 KST ±1min detection (market day).
pull_worker:
- _run_post_close_cycle: daily fetch (60일) + chronos batch predict →
  state.chronos_predictions + state.daily_ohlcv.
- update_minute_momentum_for_all: 매 cycle 마다 state.minute_momentum 갱신.
- poll_loop signature 확장 (chronos optional).

45 tests pass.

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

signal_v2/scheduler.py

@@ -76,6 +76,14 @@ def _seconds_until_nxt_or_market_open(now: datetime) -> float:
     return 86400.0
 
 
+def _is_post_close_trigger(now: datetime) -> bool:
+    """16:00 KST ±1분 (post-close cycle 트리거). 평일/영업일만."""
+    if not _is_market_day(now):
+        return False
+    t = now.time()
+    return time(16, 0) <= t < time(16, 1)
+
+
 def _seconds_until_next_market_open(now: datetime) -> float:
     """다음 영업일의 07:00 KST 까지 초수 (휴장일/주말용)."""
     candidate = now.replace(hour=7, minute=0, second=0, microsecond=0)