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/strategy.py

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+"""Strategy C: 변동성 돌파 AND 모멘텀 동시 충족 시 매수 신호."""
+
+import logging
+
+from .market import get_current_price, get_ohlcv
+
+logger = logging.getLogger(__name__)
+
+# 변동성 돌파 계수 (래리 윌리엄스 기본값)
+BREAKOUT_K = 0.5
+# 모멘텀 이동평균 기간
+MA_PERIOD = 20
+# 거래량 급증 배수
+VOLUME_MULTIPLIER = 2.0
+
+
+def check_volatility_breakout(ticker: str) -> bool:
+    """변동성 돌파 조건: 현재가 > 오늘 시가 + 전일 변동폭 × K."""
+    df = get_ohlcv(ticker, count=2)
+    if df is None or len(df) < 2:
+        return False
+
+    prev = df.iloc[-2]
+    today = df.iloc[-1]
+    target = today["open"] + (prev["high"] - prev["low"]) * BREAKOUT_K
+    current = get_current_price(ticker)
+
+    if current is None:
+        return False
+
+    result = current > target
+    if result:
+        logger.debug(f"[변동성돌파] {ticker} 현재가={current:,.0f} 목표가={target:,.0f}")
+    return result
+
+
+def check_momentum(ticker: str) -> bool:
+    """모멘텀 조건: 현재가 > MA20 AND 오늘 거래량 > 20일 평균 × 2."""
+    df = get_ohlcv(ticker, count=MA_PERIOD + 1)
+    if df is None or len(df) < MA_PERIOD + 1:
+        return False
+
+    ma = df["close"].iloc[-MA_PERIOD:].mean()
+    avg_vol = df["volume"].iloc[:-1].mean()  # 오늘 제외한 20일 평균
+    today_vol = df["volume"].iloc[-1]
+    current = get_current_price(ticker)
+
+    if current is None:
+        return False
+
+    price_ok = current > ma
+    vol_ok = today_vol > avg_vol * VOLUME_MULTIPLIER
+    result = price_ok and vol_ok
+
+    if result:
+        logger.debug(
+            f"[모멘텀] {ticker} 현재가={current:,.0f} MA20={ma:,.0f} "
+            f"오늘거래량={today_vol:.1f} 평균={avg_vol:.1f}"
+        )
+    return result
+
+
+def should_buy(ticker: str) -> bool:
+    """Strategy C: 변동성 돌파 AND 모멘텀 모두 충족 시 True."""
+    vb = check_volatility_breakout(ticker)
+    if not vb:
+        return False
+    mo = check_momentum(ticker)
+    return vb and mo