feat: initial upbit auto-trader implementation

Strategy C: volatility breakout (Larry Williams K=0.5) AND momentum
(MA20 + 2x volume surge) must both trigger for a buy signal.

Hard rules:
- Trailing stop: sell when price drops -10% from peak
- Max budget: 1,000,000 KRW total, up to 3 positions (333,333 KRW each)
- Scan top 20 KRW tickers by 24h trading volume every 60s
- Monitor positions every 10s

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

core/monitor.py

@@ -0,0 +1,58 @@
+"""트레일링 스탑 감시 - 백그라운드 스레드에서 실행."""
+
+import logging
+import time
+
+from .market import get_current_price
+from . import trader
+
+logger = logging.getLogger(__name__)
+
+STOP_LOSS_PCT = 0.10   # 최고가 대비 -10%
+CHECK_INTERVAL = 10    # 10초마다 체크
+
+
+def _check_stop(ticker: str, pos: dict) -> None:
+    """단일 포지션 스탑 체크."""
+    current = get_current_price(ticker)
+    if current is None:
+        return
+
+    # 최고가 갱신
+    trader.update_peak(ticker, current)
+
+    # 최신 peak_price 읽기 (update 후)
+    pos = trader.get_positions().get(ticker)
+    if pos is None:
+        return
+
+    peak = pos["peak_price"]
+    buy_price = pos["buy_price"]
+    drop_from_peak = (peak - current) / peak
+
+    # 로그 (보유 중 상태 확인)
+    pnl = (current - buy_price) / buy_price * 100
+    logger.info(
+        f"[감시] {ticker} 현재={current:,.0f} | "
+        f"최고={peak:,.0f} | 하락={drop_from_peak:.1%} | 수익률={pnl:+.1f}%"
+    )
+
+    if drop_from_peak >= STOP_LOSS_PCT:
+        reason = (
+            f"트레일링스탑 | 최고가={peak:,.0f}원 → "
+            f"현재={current:,.0f}원 ({drop_from_peak:.1%} 하락)"
+        )
+        trader.sell(ticker, reason=reason)
+
+
+def run_monitor(interval: int = CHECK_INTERVAL) -> None:
+    """전체 포지션 감시 루프."""
+    logger.info(f"모니터 시작 (체크 주기={interval}초, 스탑={STOP_LOSS_PCT:.0%})")
+    while True:
+        positions_snapshot = dict(trader.get_positions())
+        for ticker, pos in positions_snapshot.items():
+            try:
+                _check_stop(ticker, pos)
+            except Exception as e:
+                logger.error(f"모니터 오류 {ticker}: {e}")
+        time.sleep(interval)